MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'Chemistry' source. Mon, 06 Feb 2012 12:54:56 +0100 http://www.medworm.com/index.php?rid=5618453&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22249908%26dopt%3DAbstract Authors: Wang Y, Zhang J, Huang L, He D, Ma L, Ouyang J, Jiang F Abstract We have developed a novel application for DNA oligonucleotide-stabilized Ag nanoclusters in fluorescent imaging of human serum proteins after native polyacrylamide gel electrophoresis (PAGE). Oligonucleotide-stabilized Ag nanoclusters were used as fluorescent probes for direct detection of proteins after native PAGE. Some relatively low-abundance proteins, such as α-1-antichymotrypsin (ACT) and α-2-glycoprotein 1, zinc (ZAG) were easily detected by oligonucleotide-stabilized Ag nanocluster-based fluorescent imaging and identified by MS and MS/MS techniques, without the need of expensive antibodies or tedious immunoassay procedures. The pH condition for the oligonucleotide-stabilized Ag nanocluster solutio... Chemistry journals http://www.medworm.com/rss/comments.php?id=5618453 Sun, 22 Jan 2012 16:25:06 +0100 5618453 http://www.medworm.com/index.php?rid=5618452&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22249969%26dopt%3DAbstract In this study, the fluorescent imaging conditions, such as the buffer solution, pH value, buffer concentration and quantity of Si QDs, were optimized and the possible mechanisms of Si QDs-protein interaction were analyzed. The mode of Si QDs and human serum albumin association was found to occur by hydrogen bond interactions; this was probably attributed to the interaction between the amino group of amine-terminated Si QDs and the carboxyl group of proteins. Meanwhile, human serum proteins separated by native 1D and native 2D electrophoresis were detected by Si QD-based fluorescent imaging. Some proteins, such as isoform 1 of α-1-antitrypsin, complement C3 (Fragment) and hemopexin, which were identified by mass spectrometry (MS), were easily detected by using Si QDs, but n... Chemistry journals http://www.medworm.com/rss/comments.php?id=5618452 Sun, 22 Jan 2012 16:24:55 +0100 5618452 http://www.medworm.com/index.php?rid=5618451&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22250055%26dopt%3DAbstract Authors: Kuang Y, Cui Y, Zhang Y, Yu Y, Zhang X, Chen J Abstract Carbon nanotubes (CNTs) were non-covalently functionalized by 1-pyrenecarboxaldehyde (PCA) via ππ stacking interactions. PCA not only acts as the reductant for the deposition of PtRu nanoparticles, but the oxidation product of PCA can also effectively anchor and stabilize the in-situ-produced PtRu NPs on the surface of CNTs. Transmission electron microscopy demonstrates that PtRu NPs are uniformly dispersed on the surface of CNTs with small particles sizes of about 1.7 nm. The obtained PtRu-NP/CNT composites have higher electrochemical surface areas, electrocatalytic activities, and better stability towards methanol oxidation compared to PtRu NPs supported on pristine CNTs. PMID: 22250055 [PubMed - in... Chemistry journals http://www.medworm.com/rss/comments.php?id=5618451 Sun, 22 Jan 2012 16:24:45 +0100 5618451 http://www.medworm.com/index.php?rid=5618450&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22262356%26dopt%3DAbstract Authors: PMID: 22262356 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5618450 Sun, 22 Jan 2012 16:24:35 +0100 5618450 http://www.medworm.com/index.php?rid=5618449&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22262357%26dopt%3DAbstract Authors: Yuan W, Wei Y, Shi M, Li Y Abstract Radical transformers: The chemical transformation of vinylidenecyclopropanes with diphenyl diselenide in the presence of AIBN and upon heating gives the corresponding bicyclo[3.1.0]hexane derivatives in good yields. These compounds undergo thermal-induced radical 1,4-hydrogen shifts through a ring-opening pathway of allylic cyclopropane to give the corresponding cyclohexene derivatives stereoselectively in good yields at 200 °C. PMID: 22262357 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5618449 Sun, 22 Jan 2012 16:24:24 +0100 5618449 http://www.medworm.com/index.php?rid=5618448&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22262358%26dopt%3DAbstract Authors: PMID: 22262358 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5618448 Sun, 22 Jan 2012 16:24:13 +0100 5618448 http://www.medworm.com/index.php?rid=5595006&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22234879%26dopt%3DAbstract Authors: Artacho J, Ascic E, Rantanen T, Karlsson J, Wallentin CJ, Wang R, Wendt OF, Harmata M, Snieckus V, Wärnmark K Abstract Let's do the twist: The first twisted bis-amide is obtained by the benzylic oxidation of Tröger's base (TB). Kinetic studies of its acidic hydrolysis reveal that the hydrolysis is to a large extent funneled through doubly protonated species. PMID: 22234879 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5595006 Mon, 16 Jan 2012 15:16:08 +0100 5595006 http://www.medworm.com/index.php?rid=5595000&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237962%26dopt%3DAbstract Authors: Tahsini L, Kotani H, Lee YM, Cho J, Nam W, Karlin KD, Fukuzumi S Abstract The four-electron reduction of dioxygen by decamethylferrocene (Fc*) to water is efficiently catalyzed by a binuclear copper(II) complex (1) and a mononuclear copper(II) complex (2) in the presence of trifluoroacetic acid in acetone at 298 K. Fast electron transfer from Fc* to 1 and 2 affords the corresponding Cu(I) complexes, which react at low temperature (193 K) with dioxygen to afford the η(2) :η(2) -peroxo dicopper(II) (3) and bis-μ-oxo dicopper(III) (4) intermediates, respectively. The rate constants for electron transfer from Fc* and octamethylferrocene (Me(8) Fc) to 1 as well as electron transfer from Fc* and Me(8) Fc to 3 were determined at various temperatures, leading to activation ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595000 Mon, 16 Jan 2012 15:15:13 +0100 5595000 http://www.medworm.com/index.php?rid=5594917&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241752%26dopt%3DAbstract Authors: PMID: 22241752 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594917 Mon, 16 Jan 2012 15:12:46 +0100 5594917 http://www.medworm.com/index.php?rid=5594916&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241753%26dopt%3DAbstract Authors: Liu Y, Tang Z Abstract Nature bestows many gifts upon us, among which countless biomolecules have the ability to bridge metal ions and exert the important function in biology. By taking advantage of specific interactions between metal ions and biomolecules, this article highlights a novel concept for construction of nanoscale biocoordination polymers through replacement of synthetic organic molecules with natural biomolecules as building blocks. The most recent advances are summarized and future challenges are discussed. It can be anticipated that nanoscale biocoordination polymers will become a diverse and rapidly growing class of novel materials and potentially lead to a breakthrough in biological applications. PMID: 22241753 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594916 Mon, 16 Jan 2012 15:12:35 +0100 5594916 http://www.medworm.com/index.php?rid=5594915&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241754%26dopt%3DAbstract Authors: Deng YX, Xie JP, Zhang WW, Yin P, Yu J, He L Abstract Rocky rhodium: The oxidative amidation of aromatic ethers with no substituents in the para position catalyzed by rhodium acetate was achieved in moderate yields by using ditrifluoroacetoxyiodobenzene as the oxidant under mild conditions (RT). PMID: 22241754 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594915 Mon, 16 Jan 2012 15:12:24 +0100 5594915 http://www.medworm.com/index.php?rid=5594914&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241755%26dopt%3DAbstract Authors: PMID: 22241755 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594914 Mon, 16 Jan 2012 15:12:13 +0100 5594914 http://www.medworm.com/index.php?rid=5595014&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228491%26dopt%3DAbstract Authors: PMID: 22228491 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5595014 Mon, 16 Jan 2012 05:00:00 +0100 5595014 http://www.medworm.com/index.php?rid=5595013&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22228492%26dopt%3DAbstract Authors: PMID: 22228492 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5595013 Mon, 16 Jan 2012 05:00:00 +0100 5595013 http://www.medworm.com/index.php?rid=5594927&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241443%26dopt%3DAbstract Authors: Ikeda K, Uosaki K Abstract Optical antennas can enhance the efficiency of photon-molecule interactions. To design efficient antenna structures, it is essential to consider physicochemical aspects in addition to electromagnetic considerations. Specifically, chemical interactions between optical antennas and molecules have to be controlled to enhance the overall efficiency. For this purpose, sphere-plane nanostructures are suitable optical antennas for molecular-modified functional electrode systems when a well-defined electrode is utilized as a platform. PMID: 22241443 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594927 Fri, 13 Jan 2012 05:00:00 +0100 5594927 http://www.medworm.com/index.php?rid=5594925&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241482%26dopt%3DAbstract Dramatically Enhanced Solid-State Electrochemiluminescence of CdTe Quantum Dots Composed with TiO(2) Nanoparticles. Chemistry. 2012 Jan 13; Authors: Ding SN, Gao BH, Shan D, Sun YM, Cosnier S Abstract Shining brightly: Several tens to hundreds of times enhanced solid-state electrochemiluminescence (ECL) of CdTe quantum dots (CdTe-QDs) was realized by combining them with TiO(2) nanoparticles. The mechanism was due to the synergetic effect between titania and CdTe-QDs during the ECL process in H(2) O(2) solution. PMID: 22241482 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594925 Fri, 13 Jan 2012 05:00:00 +0100 5594925 http://www.medworm.com/index.php?rid=5594924&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241552%26dopt%3DAbstract Authors: Waki M, Mizoshita N, Maegawa Y, Hasegawa T, Tani T, Shimada T, Inagaki S Abstract Enhanced fluorescence detection of metal ions was realized in a system consisting of a fluorescent 2,2'-bipyridine (BPy) receptor and light-harvesting periodic mesoporous organosilica (PMO). The fluorescent BPy receptor with two silyl groups was synthesized and covalently attached to the pore walls of biphenyl (Bp)-bridged PMO powder. The fluorescence intensity from the BPy receptor was significantly enhanced by the light-harvesting property of Bp-PMO, that is, the energy funneling into the BPy receptor from a large number of Bp groups in the PMO framework which absorbed UV light effectively. The enhanced emission of the BPy receptor was quenched upon the addition of a low concentration of Cu... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594924 Fri, 13 Jan 2012 05:00:00 +0100 5594924 http://www.medworm.com/index.php?rid=5594923&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241585%26dopt%3DAbstract Authors: Huber C, Kraus F, Hanzlik M, Eisenreich W, Wächtershäuser G Abstract Research into the origin of evolution is polarized between a genetics-first approach, with its focus on polymer replication, and a metabolism-first approach that takes aim at chemical reaction cycles. Taking the latter approach, we explored reductive carbon fixation in a volcanic hydrothermal setting, driven by the chemical potential of quenched volcanic fluids for converting volcanic C1 compounds into organic products by transition-metal catalysts. These catalysts are assumed to evolve by accepting ever-new organic products as ligands for enhancing their catalytic power, which in turn enhances the rates of synthetic pathways that give rise to ever-new organic products, with the overall effect of a self... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594923 Fri, 13 Jan 2012 05:00:00 +0100 5594923 http://www.medworm.com/index.php?rid=5594922&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241603%26dopt%3DAbstract Tuning the Physicochemical Properties of Diverse Phenolic Ionic Liquids for Equimolar CO(2) Capture by the Substituent on the Anion. Chemistry. 2012 Jan 13; Authors: Wang C, Luo H, Li H, Zhu X, Yu B, Dai S Abstract Phenolic ionic liquids for the efficient and reversible capture of CO(2) were designed and prepared from phosphonium hydroxide and substituted phenols. The electron-withdrawing or electron-donating ability, position, and number of the substituents on the anion of these ionic liquids were correlated with the physicochemical properties of the ionic liquids. The results show that the stability, viscosity, and CO(2) -capturing ability of these ionic liquids were significantly affected by the substituents. Furthermore, the relationship between the decomposition temper... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594922 Fri, 13 Jan 2012 05:00:00 +0100 5594922 http://www.medworm.com/index.php?rid=5594921&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241631%26dopt%3DAbstract Authors: Larini P, Kefalidis CE, Jazzar R, Renaudat A, Clot E, Baudoin O Abstract The palladium-catalyzed β-arylation of ester enolates with aryl bromides was studied both experimentally and computationally. First, the effect of the ligand on the selectivity of the α/β-arylation reactions of ortho- and meta-fluorobromobenzene was described. Selective β-arylation was observed for the reaction of o-fluorobromobenzene with a range of biarylphosphine ligands, whereas α-arylation was predominantly observed with m-fluorobromobenzene for all ligands except DavePhos, which gave an approximate 1:1 mixture of α-/β-arylated products. Next, the effect of the substitution pattern of the aryl bromide reactant was studied with DavePhos as the ligand. We showed that electronic factors playe... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594921 Fri, 13 Jan 2012 05:00:00 +0100 5594921 http://www.medworm.com/index.php?rid=5594920&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241648%26dopt%3DAbstract Authors: Kang MY, Lim CS, Kim HS, Seo EW, Kim HM, Kwon O, Cho BR Abstract Molecular imaging by two-photon microscopy (TPM) has become indispensable to the study of biology/medicine owing to its capability of imaging deep inside intact tissues. To make TPM a more-versatile tool, a large variety of two-photon probes are needed. Herein, we report a new two-photon fluorescent probe (ANi2) that can be excited by 750 nm femtosecond pulses and detect Ni(2+) ions in fresh fish organs at 90-175 μm depth without interference from the pH value or from other biologically relevant species through the use of TPM. TPM images of fish organs labeled with ANi2 revealed that Ni(2+) ions accumulate in fish organs in the order: kidney > heart > gill ≥ liver. Moreover, a linear relationship... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594920 Fri, 13 Jan 2012 05:00:00 +0100 5594920 http://www.medworm.com/index.php?rid=5594919&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241661%26dopt%3DAbstract Monodisperse REPO(4) (RE=Yb, Gd, Y) Hollow Microspheres Covered with Nanothorns as Affinity Probes for Selectively Capturing and Labeling Phosphopeptides. Chemistry. 2012 Jan 13; Authors: Cheng G, Zhang JL, Liu YL, Sun DH, Ni JZ Abstract Rare-earth phosphate microspheres with unique structures were developed as affinity probes for the selective capture and tagging of phosphopeptides. Prickly REPO(4) (RE=Yb, Gd, Y) monodisperse microspheres, that have hollow structures, low densities, high specific surface areas, and large adsorptive capacities were prepared by an ion-exchange method. The elemental compositions and crystal structures of these affinity probes were confirmed by energy-dispersive spectroscopy (EDS), powder X-ray diffraction (XRD), and Fourier-transform infrared... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594919 Fri, 13 Jan 2012 05:00:00 +0100 5594919 http://www.medworm.com/index.php?rid=5594918&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22241666%26dopt%3DAbstract Authors: Liu B, Wang Z, Wu N, Li M, You J, Lan J Abstract All the colors of the rainbow! A full coverage of emission wavelengths in the visible region (405-616 nm) with large Stokes shifts in C3-Indo-Fluor may be straightforwardly and succinctly achieved by the palladium-catalyzed direct CH arylation of indolizines at the C3 position of the pyrrole ring. The fluorophores have successfully marked A375 cells. PMID: 22241666 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594918 Fri, 13 Jan 2012 05:00:00 +0100 5594918 http://www.medworm.com/index.php?rid=5595005&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237811%26dopt%3DAbstract Authors: Aydogan A, Akar A Abstract Calixpyrrole-based oligomeric compounds were synthesized by "click chemistry" from the corresponding alkyne- and azide-functionalized calix[4]pyrroles. Calix[4]pyrrole 3, possessing an alkyne functional group, was prepared through a mixed condensation of pyrrole with acetone and but-3-ynyl 4-oxopentanoate. Another alkyne-group-containing calix[4]pyrrole 5 was obtained by treatment of 4'-hydroxyphenyl-functionalized calixpyrrole 4 with propargyl bromide. Tetrakis(azidopentyl)-functionalized calix[4]pyrrole 7 was synthesized by reacting NaN(3) with tetrabromopentyltetraethylcalix[4]pyrrole 6, which was prepared through a condensation reaction of pyrrole and 7-bromohept-2-one. Oligomeric calixpyrrole compounds were found to be capable of extracting ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595005 Wed, 11 Jan 2012 05:00:00 +0100 5595005 http://www.medworm.com/index.php?rid=5595004&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237868%26dopt%3DAbstract Authors: Paderes MC, Belding L, Fanovic B, Dudding T, Keister JB, Chemler SR Abstract Alkene difunctionalization reactions are important in organic synthesis. We have recently shown that copper(II) complexes can promote and catalyze intramolecular alkene aminooxygenation, carboamination, and diamination reactions. In this contribution, we report a combined experimental and theoretical examination of the mechanism of the copper(II)-promoted olefin aminooxygenation reaction. Kinetics experiments revealed a mechanistic pathway involving an equilibrium reaction between a copper(II) carboxylate complex and the γ-alkenyl sulfonamide substrate and a rate-limiting intramolecular cis-addition of NCu across the olefin. Kinetic isotope effect studies support that the cis-aminocupration is... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595004 Wed, 11 Jan 2012 05:00:00 +0100 5595004 http://www.medworm.com/index.php?rid=5595003&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237915%26dopt%3DAbstract Authors: Joy S, Pal P, Mondal TK, Talapatra GB, Goswami S Abstract Neutral tris-chelated chromium complex [Cr(L(a) )(3) ] (1 a), and its surfactant derivatives [Cr(L(b) )(3) ] (1 b), [Cr(L(c) )(3) ] (1 c), and [Cr(L(d) )(3) ] (1 d) (where L(a) =2-(4'-methoxyphenylazo)pyridine, L(b) =2-(4'-butyloxyphenylazo)pyridine, L(c) =2-(4'-octyloxyphenylazo)pyridine, and L(d) =2-(4'-dodecyloxyphenylazo)pyridine) were synthesized. The molecular structure of compound 1 a, determined by X-ray diffraction, showed that the local geometry around the metal center is a distorted octahedral with meridional coordination of the ligands. The structural parameters, spectroscopic data, and density functional theory (DFT) calculations on representative complex 1 a suggest that ligand L(a) is pred... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595003 Wed, 11 Jan 2012 05:00:00 +0100 5595003 http://www.medworm.com/index.php?rid=5595002&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237933%26dopt%3DAbstract Authors: Li Manni G, Dzubak AL, Mulla A, Brogden DW, Berry JF, Gagliardi L Abstract To gain insights into the trends in metal-metal multiple bonding among the Group 6 elements, density functional theory has been employed in combination with multiconfigurational methods (CASSCF and CASPT2) to investigate a selection of bimetallic, multiply bonded compounds. For the compound [Ar-MM-Ar] (Ar=2,6-(C(6) H(5) )(2) -C(6) H(3) , M=Cr, Mo, W) the effect of the Ar ligand on the M(2) core has been compared with the analogous [Ph-MM-Ph] (Ph=phenyl, M=Cr, Mo, W) compounds. A set of [M(2) (dpa)(4) ] (dpa=2,2'-dipyridylamide, M=Cr, Mo, W, U) compounds has also been investigated. All of the compounds studied here show important multiconfigurational behavior. For the Mo(2) and W(2) compounds, the ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595002 Wed, 11 Jan 2012 05:00:00 +0100 5595002 http://www.medworm.com/index.php?rid=5595001&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237960%26dopt%3DAbstract Authors: Kuriyama M, Hamaguchi N, Onomura O Abstract Selective and efficient: The copper(II)-catalyzed selective monoarylation of vicinal diols with diaryliodonium triflates was successfully developed. In this catalytic process high chemoselectivity was achieved, even in the presence of a 1:1 mixture of the 1,2-diol and the mono-ol, and a wide range of substrates was tolerated, giving the monoarylated products in good to excellent yields. PMID: 22237960 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5595001 Wed, 11 Jan 2012 05:00:00 +0100 5595001 http://www.medworm.com/index.php?rid=5594999&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22237963%26dopt%3DAbstract Authors: Cubillas AM, Schmidt M, Scharrer M, Euser TG, Etzold BJ, Taccardi N, Wasserscheid P, Russell PS Abstract Photonic crystal fibers as microreactors: Photonic crystal fibers can be used as microreactors. As an example, the illustration shows the difference in size between a 10 cm cuvette (left), and a photonic crystal fiber (right; not to scale). PMID: 22237963 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594999 Wed, 11 Jan 2012 05:00:00 +0100 5594999 http://www.medworm.com/index.php?rid=5594998&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22238020%26dopt%3DAbstract Authors: Partyka DV, Teets TS, Zeller M, Updegraff JB, Hunter AD, Gray TG Abstract A series of di(gold(I) aryls), L(AuR)(2) (L=DPEphos, DBFphos, or Xantphos; R=1-naphthyl, 2-naphthyl, 9-phenanthryl, or 1-pyrenyl), have been prepared. The complexes were characterized by multinuclear NMR spectroscopy, static and time-dependent optical spectroscopy, mass spectrometry, microanalysis, and X-ray crystallography. In addition, DFT calculations on model dinuclear gold complexes have been used to examine the electronic structures. Photophysical properties of the dinuclear complexes have been compared to mononuclear analogues. Low-temperature excited-state lifetimes for both the mononuclear and dinuclear complexes in toluene indicate triplet-state emission. Time-resolved DFT calculations sugg... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594998 Wed, 11 Jan 2012 05:00:00 +0100 5594998 http://www.medworm.com/index.php?rid=5594997&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22238030%26dopt%3DAbstract Authors: Pablo O, Guijarro D, Kovács G, Lledós A, Ujaque G, Yus M Abstract A highly efficient Ru catalyst based on an achiral, very simple, and inexpensive amino alcohol ligand (2-amino-2-methylpropan-1-ol) has been developed for the asymmetric transfer hydrogenation (ATH) of chiral N-(tert-butylsulfinyl)imines. This complex is able to catalyze the ATH of both aromatic and the most challenging aliphatic sulfinylimines by using isopropyl alcohol as the hydrogen source. The diastereoselective reduction of aromatic, heteroaromatic, and aliphatic sulfinylketimines, including sterically congested cases, over short reaction times (1-4 h), followed by desulfinylation of the nitrogen atom, affords the corresponding highly enantiomerically enriched (ee up to >99 %) α-branched prim... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594997 Wed, 11 Jan 2012 05:00:00 +0100 5594997 http://www.medworm.com/index.php?rid=5594996&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22238129%26dopt%3DAbstract Carbodiphosphorane Analogues E(PPh(3) )(2) with E=C-Pb: A Theoretical Study with Implications for Ligand Design. Chemistry. 2012 Jan 11; Authors: Takagi N, Tonner R, Frenking G Abstract Quantum-chemical calculations at the BP86/TZVPP level have been carried out for the heavy Group 14 homologues of carbodiphosphorane E(PPh(3) )(2) , where E=Si, Ge, Sn, Pb, which are experimentally unknown so far. The results of the theoretical investigation suggest that the tetrelediphosphoranes E(PPh(3) )(2) (1 E) are stable compounds that could become isolated in a condensed phase. The molecules possess donor-acceptor bonds Ph(3) P→E←PPh(3) to a bare tetrele atom E, which retains its four valence electrons as two electron lone pairs. The analysis of the bonding situation and the calc... Chemistry journals http://www.medworm.com/rss/comments.php?id=5594996 Wed, 11 Jan 2012 05:00:00 +0100 5594996 http://www.medworm.com/index.php?rid=5594940&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22238176%26dopt%3DAbstract Authors: Khan BA, Buba AE, Gooßen LJ Abstract Introducing CF(3) : Arylboronic acid pinacol esters are converted into the corresponding benzotrifluorides with the easy-to-use one-component trifluoromethylating reagent potassium (trifluoromethyl)trimethoxyborate, mediated by copper acetate under an oxygen atmosphere. PMID: 22238176 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5594940 Wed, 11 Jan 2012 05:00:00 +0100 5594940 http://www.medworm.com/index.php?rid=5595008&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22234833%26dopt%3DAbstract Authors: Comba P, Gahan LR, Hanson GR, Mereacre V, Noble CJ, Powell AK, Prisecaru I, Schenk G, Zajaczkowski-Fischer M Abstract The synthesis and characterization of a novel dinucleating ligand L (L=4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam) and its μ-oxo-bridged diferric complex [(H(2) L){Fe(III) (2) (O)}(Cl)(4) ](2+) are reported. This diiron(III) complex is the first example of a truly functional purple acid phosphatase (PAP) mimic as it accelerates the hydrolysis of the activated phosphomonoester 2,4-dinitrophenyl phosphate (DNPP). The spectroscopic and kinetic data indicate that only substrates that are monodentately bound to one of the two ferric ions can be attacked by a suitable nucleophile. This is, most probably, a terminal iron(III)-bound hy... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595008 Tue, 10 Jan 2012 05:00:00 +0100 5595008 http://www.medworm.com/index.php?rid=5595007&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22234862%26dopt%3DAbstract Authors: Trogu E, Vinattieri C, De Sarlo F, Machetti F Abstract Base-catalysed condensation reactions of nitroacetic esters with dipolarophiles to give isoxazole derivatives proceed faster, and often with higher yields, in the presence of water than in organic solvents such as chloroform. Kinetic profiles show that induction times are greatly reduced when the reaction is performed "in water" or "on water". Any specificity of the base related to H-bonding ability observed in chloroform is lost in water: all bases either organic or inorganic give the same result that is simply depending on concentration. A 0.1 molar ratio of base to nucleophile gives the best conversion, whereas addition of one equivalent of base or strong acid prevents the reaction from occurring. These results fi... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595007 Tue, 10 Jan 2012 05:00:00 +0100 5595007 http://www.medworm.com/index.php?rid=5595012&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231392%26dopt%3DAbstract Authors: Junggeburth SC, Schwinghammer K, Virdi KS, Scheu C, Lotsch BV Abstract The transfer of supramolecular templating to the realm of metal-organic frameworks opens up new avenues to the design of novel hierarchically structured materials. We demonstrate the first synthesis of mesostructured zinc imidazolates in the presence of the cationic surfactant cetyltrimethylammonium bromide (CTAB), which acts as a template giving rise to ordered lamellar hybrid materials. A high degree of order spanning the atomic and mesoscale was ascertained by powder X-ray diffraction, electron diffraction, as well as solid-state NMR and IR spectroscopy. The metrics of the unit cells obtained for the zinc methylimidazolate and imidazolate species are a=(11.43±0.45), b=(9.55±0.35), c=(27.19±0.34)�... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595012 Mon, 09 Jan 2012 05:00:00 +0100 5595012 http://www.medworm.com/index.php?rid=5595011&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231439%26dopt%3DAbstract Authors: Bedini E, De Castro C, De Rosa M, Di Nola A, Restaino OF, Schiraldi C, Parrilli M Abstract The extraction from natural sources of Chondroitin sulfate (CS), a polysaccharide used for management of osteoarthritis, leads to very complex mixtures. The synthesis of CS by chemical modification of other polysaccharides has seldom been reported due to the intrinsic complexity that arises from fine chemical modifications of the polysaccharide structure. In view of the growing interest in expanding the application of CS to pharmacological fields other than osteoarthritis treatment, we launched a program to find new sources of known or even unprecedented CS polysaccharides. As part of this program, we report herein on an investigation of the use of a cyclic orthoester group to select... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595011 Mon, 09 Jan 2012 05:00:00 +0100 5595011 http://www.medworm.com/index.php?rid=5595010&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231489%26dopt%3DAbstract The Importance of Stereochemically Active Lone Pairs For Influencing Pb(II) and As(III) Protein Binding. Chemistry. 2012 Jan 9; Authors: Zampella G, Neupane KP, De Gioia L, Pecoraro VL Abstract The toxicity of heavy metals, which is associated with the high affinity of the metals for thiolate rich proteins, constitutes a problem worldwide. However, despite this tremendous toxicity concern, the binding mode of As(III) and Pb(II) to proteins is poorly understood. To clarify the requirements for toxic metal binding to metalloregulatory sensor proteins such as As(III) in ArsR/ArsD and Pb(II) in PbrR or replacing Zn(II) in δ-aminolevulinc acid dehydratase (ALAD), we have employed computational and experimental methods examining the binding of these heavy metals to designed pept... Chemistry journals http://www.medworm.com/rss/comments.php?id=5595010 Mon, 09 Jan 2012 05:00:00 +0100 5595010 http://www.medworm.com/index.php?rid=5595009&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22231520%26dopt%3DAbstract Authors: Broncel M, Krause E, Schwarzer D, Hackenberger CP Abstract Site-specifically phosphorylated tau: A semisynthetic strategy has been applied for the first time to generate a phosphorylated and biotinylated fully functional tau protein. The presented methodology allows for an unambiguous verification of individual phosphorylation sites on tau and significantly improves its purification. PMID: 22231520 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5595009 Mon, 09 Jan 2012 05:00:00 +0100 5595009 http://www.medworm.com/index.php?rid=5575926&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213364%26dopt%3DAbstract Authors: PMID: 22213364 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575926 Mon, 09 Jan 2012 05:00:00 +0100 5575926 http://www.medworm.com/index.php?rid=5575925&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213365%26dopt%3DAbstract Authors: PMID: 22213365 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575925 Mon, 09 Jan 2012 05:00:00 +0100 5575925 http://www.medworm.com/index.php?rid=5575909&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223125%26dopt%3DAbstract Authors: Nilsson Lill SO, Ryberg P, Rein T, Bennström E, Norrby PO Abstract The regioselectivity in the palladium-catalyzed Heck coupling reaction between an aryl halide and ethyl vinyl ether with four different phosphine ligands: PPh(n) tBu(m) (n=0-3, m=3-n) has been investigated both experimentally and computationally. A zigzag selectivity pattern was experimentally observed upon consecutive replacement of Ph by tBu in the phosphine ligand. Use of a standard DFT method (B3LYP) was shown to give a correct prediction of product preference. However, the trend in relative selectivity among the different ligands could not be correctly described. The use of a more recent DFT functional (M06) parameterized to reproduce dispersion interactions resulted in an improved description. For th... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575909 Thu, 05 Jan 2012 05:00:00 +0100 5575909 http://www.medworm.com/index.php?rid=5575908&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223148%26dopt%3DAbstract Authors: Kumar B, Beyler M, Kubiak CP, Ott S Abstract Let there be light! A dithiolate-bridged [FeFe] complex with structural features of the [FeFe] hydrogenase active site has been photoelectrochemically reduced by a p-type Si photocathode at a potential 500 mV less negative compared with a glassy carbon electrode. In the presence of HClO(4) , hydrogen generation has been achieved at a photovoltage of 600 mV with a (105±5) % Faradaic efficiency. PMID: 22223148 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575908 Thu, 05 Jan 2012 05:00:00 +0100 5575908 http://www.medworm.com/index.php?rid=5575907&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223183%26dopt%3DAbstract Authors: Chang KC, Lin JL, Shen YT, Hung CY, Chen CY, Sun SS Abstract A series of platinum(II) acetylide complexes with elaborate long-chain pyridine-2,6-dicarboxamides was synthesized. These metal complexes are capable of immobilizing organic solvents to form luminescent metallogels through a combination of intermolecular hydrogen bonding, aromatic π-π, and van der Waals interactions. Fibrillar morphologies were identified by TEM for these metallogels. Unique photophysical properties associated with the sol-to-gel transition have been disclosed with luminescence enhancement at elevated temperatures, which is in sharp contrast to typical thermotropic organogels or metallogels reported in the literature. Such unusual luminescence enhancement is attributed to the increased degree o... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575907 Thu, 05 Jan 2012 05:00:00 +0100 5575907 http://www.medworm.com/index.php?rid=5575906&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223216%26dopt%3DAbstract Authors: Yin BC, You M, Tan W, Ye BC Abstract A novel probe design of pyrene-disulfide molecular assembly has been proposed and its application for the fluorescence turn-on detection of mercury(II) ions (Hg(2+) ) has been demonstrated. By taking advantage of the pyrene-assisted efficient photolysis of disulfide bonds, our proposed sensing system exhibits both high selectivity and sensitivity toward Hg(2+) detection with a detection limit of 5 nM (1 ppb). PMID: 22223216 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575906 Thu, 05 Jan 2012 05:00:00 +0100 5575906 http://www.medworm.com/index.php?rid=5575903&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223231%26dopt%3DAbstract Authors: Molla MR, Ghosh S Abstract Almost pure white-light emission (fluorescence quantum yield=0.70) from a remarkably simple single-component, carboxylic acid appended naphthalenediimide (NDI) derivative has been reported. Aggregation-induced modulation of photophysical properties was attributed to hydrogen-bonding-mediated J-type π stacking among the NDI chromophores. PMID: 22223231 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575903 Thu, 05 Jan 2012 05:00:00 +0100 5575903 http://www.medworm.com/index.php?rid=5575898&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223531%26dopt%3DAbstract Authors: Braml NE, Sattler A, Schnick W Abstract Pyrolysis of prominent precursor compounds for the synthesis of carbon nitride type materials (e.g., melamine, thiourea) have been studied in detail. Molecular adducts containing monoprotonated melamium C(6) N(11) H(10) (+) and melaminium HC(3) N(3) (NH(2) )(3) (+) ions, respectively, have been identified as intermediates. The adduct C(6) N(11) H(10) Cl⋅0.5NH(4) Cl was obtained by the reaction of melamine C(3) N(3) (NH(2) )(3) with NH(4) Cl at 450 °C. During the pyrolysis of thiourea, guanidinium thiocyanate was initially formed and subsequently the melamium thiocyanate melamine adduct C(6) N(11) H(10) SCN⋅2C(3) N(3) (NH(2) )(3) was isolated at 300 °C. A second melaminium thiocyanate melamine adduct with the for... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575898 Thu, 05 Jan 2012 05:00:00 +0100 5575898 http://www.medworm.com/index.php?rid=5575893&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223588%26dopt%3DAbstract Authors: Cheng X, Li S, Jia H, Zhong A, Zhong C, Feng J, Qin J, Li Z Abstract A new series of intramolecular-charge-transfer (ICT) molecules (compounds 1, 2, and 3) were synthesized by attaching various electron-donating thiophenes groups to a triphenylamine backbone with an aldehyde group as the electron acceptor. Based on the protection reaction between ethanethiol and aldehyde, the corresponding dithioacetals (compounds S1, S2, and S3) were prepared to serve as novel colorimetric and fluorescent chemosensors for Hg(2+) ions. Also, compound S1 was further utilized to construct the chemical-reaction-based conjugated polymer probe (PS1) towards Hg(2+) ions. In the presence of as little as 10 nM Hg(2+) , compound PS1 displayed an apparent change in the fluorescent intensity. The s... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575893 Thu, 05 Jan 2012 05:00:00 +0100 5575893 http://www.medworm.com/index.php?rid=5575900&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223489%26dopt%3DAbstract Syntheses, Properties, and Photoreactions of the Hybrid Molecules Consisting of a Co(II) Mononuclear Complex and Porphyrins. Chemistry. 2012 Jan 3; Authors: Kon H, Nagata T Abstract New hybrid molecules consisting of mononuclear Co(II) complexes and porphyrin moieties were synthesized and their new photoreactions were examined. Three porphyrins with different meso-substituents (2,6-dimethoxyphenyl, 3,5-di-tert-butylphenyl, and 2,6-difluorophenyl groups) were used to change the redox potentials of the hybrid compounds. The hybrid molecules were prepared by the stepwise condensation of amide bonds. The cyclic voltammograms of these hybrid molecules showed the redox processes of both the cobalt and porphyrin moieties. The redox potentials of the porphyrins showed a systematic ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575900 Tue, 03 Jan 2012 05:00:00 +0100 5575900 http://www.medworm.com/index.php?rid=5575899&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223510%26dopt%3DAbstract Authors: Freire MG, Pereira JF, Francisco M, Rodríguez H, Rebelo LP, Rogers RD, Coutinho JA Abstract New polyethylene glycol (PEG)/ionic liquid aqueous biphasic systems (ABS) are presented. Distinct pairs of PEG polymers and ionic liquids can induce phase separation in aqueous media when dissolved at appropriate concentrations. Phase diagrams have been determined for a large array of systems at 298, 308 and 323 K. A comparison of the binodal curves allowed the analysis of the tunable structural features of the ionic liquid (i.e., anionic nature, cationic core, cationic alkyl side chain length and functionalisation, and number of alkyl substituents in the cation) and the influence of the molecular weight of the PEG polymer on the ability of these solutes to induce an ABS. It was ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575899 Tue, 03 Jan 2012 05:00:00 +0100 5575899 http://www.medworm.com/index.php?rid=5575897&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223540%26dopt%3DAbstract Reaction of a 6-Dimethylaminopentafulvene with the Mes(2) PCH(2) CH(2) B(C(6) F(5) )(2) Frustrated Lewis Pair. Chemistry. 2012 Jan 3; Authors: Xu BH, Mömming CM, Fröhlich R, Kehr G, Erker G Abstract The frustrated Lewis pair Mes(2) PCH(2) CH(2) B(C(6) F(5) )(2) reacts readily with 6-dimethylamino-6-methylfulvene at room temperature to yield the trans-1-[B(C(6) F(5) )(2) ]-2-[CH(2) CH(2) PMes(2) ] disubstituted fulvene derivative 9 that features an internal N-B contact. Thermolysis (80 °C in toluene) results in a complete isomerization to the respective 1-[B(C(6) F(5) )(2) ]-3-[CH(2) CH(2) PMes(2) ] isomer 10. Both compounds were characterized by using X-ray diffraction. A reaction scheme is formulated to rationalize the specific formation of these compounds, involving ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575897 Tue, 03 Jan 2012 05:00:00 +0100 5575897 http://www.medworm.com/index.php?rid=5575895&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223548%26dopt%3DAbstract New Cu-Based Catalysts Supported on TiO(2) Films for Ullmann S(N) Ar-Type CO Coupling Reactions. Chemistry. 2012 Jan 3; Authors: Benaskar F, Engels V, Rebrov EV, Patil NG, Meuldijk J, Thüne PC, Magusin PC, Mezari B, Hessel V, Hulshof LA, Hensen EJ, Wheatley AE, Schouten JC Abstract New routes for the preparation of highly active TiO(2) -supported Cu and CuZn catalysts have been developed for CO coupling reactions. Slurries of a titania precursor were dip-coated onto glass beads to obtain either structured mesoporous or non-porous titania thin films. The Cu and CuZn nanoparticles, synthesized using a reduction by solvent method, were deposited onto calcined films to obtain a Cu loading of 2 wt %. The catalysts were characterized by inductively coupled plasma (ICP)... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575895 Tue, 03 Jan 2012 05:00:00 +0100 5575895 http://www.medworm.com/index.php?rid=5575894&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223585%26dopt%3DAbstract Authors: Sastre F, Fornés V, Corma A, García H Abstract Deep-UV photolysis (either 165 or 185 nm) of surface hydroxy groups leads to homolytic OH bond-cleavage with the generation of oxyl radicals that can initiate the room-temperature radical-chain methane activation. Whilst in the absence of oxygen, radical coupling reactions to give low-molecular-weight alkanes are observed in the gas phase, the presence of some oxygen quenches these radicals and increases the selectivity towards C1 oxygenates (methanol, formaldehyde, and formic acid species). The nature of the solid influences the efficiency of the photochemical process and the distribution between products in the gas and solid phases. Using Beta-, delaminated ITQ2 and ITQ6, and medium-pore ZSM5 zeolites, mesoporous MCM4... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575894 Tue, 03 Jan 2012 05:00:00 +0100 5575894 http://www.medworm.com/index.php?rid=5575892&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22223603%26dopt%3DAbstract A "Clickable" Styryl Dye for Fluorescent DNA Labeling by Excitonic and Energy Transfer Interactions. Chemistry. 2012 Jan 3; Authors: Rubner MM, Holzhauser C, Bohländer PR, Wagenknecht HA Abstract Turn on and turn red: The CyIQ dye as an internal DNA label can be combined with itself and thiazole red as intrastrand fluorophore pairs. Excitonic and energy transfer interactions provide interesting alternatives for fluorescence readouts, which are either fluorescence enhancement or fluorescence color change, respectively. PMID: 22223603 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575892 Tue, 03 Jan 2012 05:00:00 +0100 5575892 http://www.medworm.com/index.php?rid=5575931&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213254%26dopt%3DAbstract Authors: Compton NA PMID: 22213254 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575931 Mon, 02 Jan 2012 05:00:00 +0100 5575931 http://www.medworm.com/index.php?rid=5575930&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213255%26dopt%3DAbstract Authors: PMID: 22213255 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575930 Mon, 02 Jan 2012 05:00:00 +0100 5575930 http://www.medworm.com/index.php?rid=5575929&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213256%26dopt%3DAbstract Authors: PMID: 22213256 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575929 Mon, 02 Jan 2012 05:00:00 +0100 5575929 http://www.medworm.com/index.php?rid=5575923&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213393%26dopt%3DAbstract Authors: Tönshoff C, Bettinger HF Abstract The synthesis of 2,3-R(2) -9,10-(OMe)(2) -substituted pentacenes (R=OMe, F, Br, CN; 1-4) from 2,3-R(2) -9,10-dimethoxy-6,13-dihydro-6,13-ethanopentacene-15,16-diones (α-diketone-bridged precursors) by photochemically induced bis-decarbonylation (Strating-Zwanenburg reaction) is described. Under matrix-isolation conditions (solid Ar, 10 K) the S(1) transitions of 1 and 2 undergo hypsochromic and those of 3 and 4 bathochromic shifts compared to parent pentacene. The S(1) transition wavelengths correlate well with the difference of substituent parameters σ(p) . A computational analysis of the excited states at the CAM-B3LYP/6-311+G** level of theory provides an assignment of the electronic transitions. Photolysis in solution at room temp... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575923 Mon, 02 Jan 2012 05:00:00 +0100 5575923 http://www.medworm.com/index.php?rid=5575921&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213427%26dopt%3DAbstract In this study we combined quantum dots (QDs) with GA in the presence of β-cyclodextrin (β-CD), and prepared β-CD/GA-functionalised QDs, which led to improved antitumor activity and induced apoptosis in hepatocarcinoma cells. These compounds showed a better selectivity for hepatic cells compared to HeLa and ECV-304 cells. Hoechst and annexin V-FITC staining and mitochondrial membrane potential (MMP) experiments proved an apoptotic effect of these compounds on HepG2 cells. At the same time, transmission electron microscopy (TEM) showed obvious features of apoptosis, for example, irregularities of nuclear shapes, mitochondria swelling, clumping and peripheral chromatin condensation, zeiosis or blebbing of the plasma membrane and formation of apoptotic bodies. It is notable that β-CD/GA-... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575921 Mon, 02 Jan 2012 05:00:00 +0100 5575921 http://www.medworm.com/index.php?rid=5575918&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213466%26dopt%3DAbstract Authors: Bates JI, Gates DP Abstract The activation of the PC bond of phosphaalkenes with electrophiles is investigated as a means to prepare and characterize unusual organophosphorus compounds. Treatment of RPCHtBu (1 a: R=tBu; 1 b: R=1-adamantyl) with HOTf (0.5 equiv) affords diphosphiranium salts [RPCHtBuPR (CH(2) tBu)]OTf ([2 a]OTf and [2 b]OTf), each containing a three-membered P(2) C ring. In contrast, the addition of MeOTf (0.5 equiv) to either 1 a or 1 b affords diphosphetanium salts [RPCHtBuP(Me)RCHtBu]OTf ([3 a]OTf and [3 b]OTf) containing four-membered P(2) C(2) heterocycles. The phosphenium triflate [tBuP(CH(2) tBu)]OTf ([5 a]OTf) and methylenephosphonium triflate [tBu(Me)PCHtBu]OTf ([7 a]OTf) are identified spectroscopica... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575918 Mon, 02 Jan 2012 05:00:00 +0100 5575918 http://www.medworm.com/index.php?rid=5575950&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213064%26dopt%3DAbstract Authors: Weber L, Eickhoff D, Marder TB, Fox MA, Low PJ, Dwyer AD, Tozer DJ, Schwedler S, Brockhinke A, Stammler HG, Neumann B Abstract Four linear π-conjugated systems with 1,3-diethyl-1,3,2-benzodiazaborolyl [C(6) H(4) (NEt)(2) B] as a π-donor at one end and dimesitylboryl (BMes(2) ) as a π-acceptor at the other end were synthesized. These unusual push-pull systems contain phenylene (1,4-C(6) H(4) ; 1), biphenylene (4,4'-(1,1'-C(6) H(4) )(2) ; 2), thiophene (2,5-C(4) H(2) S; 3), and dithiophene (5,5'-(2,2'-C(4) H(2) S)(2) ; 4) as π-conjugated bridges and different types of three-coordinate boron moieties serving as both π-donor and π-acceptor. Molecular structures of 2, 3, and 4 were determined by single-crystal X-ray diffraction. Photophysical studi... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575950 Fri, 30 Dec 2011 05:00:00 +0100 5575950 http://www.medworm.com/index.php?rid=5575935&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213187%26dopt%3DAbstract Authors: Bonnet CS, Buron F, Caillé F, Shade CM, Drahoš B, Pellegatti L, Zhang J, Villette S, Helm L, Pichon C, Suzenet F, Petoud S, Tóth E Abstract A series of novel triazole derivative pyridine-based polyamino-polycarboxylate ligands has been synthesized for lanthanide complexation. This versatile platform of chelating agents combines advantageous properties for both magnetic resonance (MR) and optical imaging applications of the corresponding Gd(3+) and near-infrared luminescent lanthanide complexes. The thermodynamic stability constants of the Ln(3+) complexes, as assessed by pH potentiometric measurements, are in the range log K(LnL) =17-19, with a high selectivity for lanthanides over Ca(2+) , Cu(2+) , and Zn(2+) . The complexes are bishydrated, an important advantage to... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575935 Fri, 30 Dec 2011 05:00:00 +0100 5575935 http://www.medworm.com/index.php?rid=5575933&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213228%26dopt%3DAbstract Authors: Florian J, Brabec V Abstract Differential scanning calorimetry (DSC) was used to measure the thermodynamic changes associated with translesion synthesis across major lesion induced in DNA by antitumor oxaliplatin [1,2-d(GG) intrastrand cross-link]. Insertion of matched nucleotides dC at the primer terminus (across unique 3'- or 5'-dG in the unplatinated template) and subsequent extensions resulted in an incremental increase in thermodynamic parameters. In contrast, incorporation of dC opposite either platinated dG in the intrastrand cross-link formed in the template strand and subsequent extensions by one nucleotide resulted only in little changes in thermodynamics. A similar thermodynamic delay was observed for a control template primer containing a dG:dT mismatch across ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575933 Fri, 30 Dec 2011 05:00:00 +0100 5575933 http://www.medworm.com/index.php?rid=5575927&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213362%26dopt%3DAbstract Authors: Cid J, Carbó JJ, Fernández E Abstract We have studied the non-conventional trans-hydroboration reaction of alkynes both experimentally and theoretically. A catalytic system based on the in situ mixture of [{Rh(cod)Cl}(2) ]/PCy(3) (cod=1,5-cyclooctadiene, Cy=cyclohexyl) has been able to activate pinacolborane and catecholborane and transfer boryl and hydride groups onto the same unhindered carbon atom of the terminal alkynes. The presence of a base (Et(3) N) favored the non-conventional trans-hydroboration over the traditional cis-hydroboration. Varying the substrate had a significant influence on the reaction, with up to 99 % conversion and 94 % regioselectivity observed for para-methyl-phenylacetylene. Both DFT and quantum mechanical/molecular mechanical ONIOM calcu... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575927 Fri, 30 Dec 2011 05:00:00 +0100 5575927 http://www.medworm.com/index.php?rid=5575924&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213391%26dopt%3DAbstract Authors: Xia AB, Xu DQ, Wu C, Zhao L, Xu ZY Abstract Self-assembled catalyst: A new kind of chiral supramolecular organocatalysts, self-assembled from chiral amines and poly(alkene glycol)s, was developed. The resulting self-assemblies were found to be highly efficient in the asymmetric catalysis of the unusual Diels-Alder reaction between cyclohexenones and nitrodienes, nitroenynes or nitroolefins, giving excellent chemo-, regio- and enantioselectivities. PMID: 22213391 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575924 Fri, 30 Dec 2011 05:00:00 +0100 5575924 http://www.medworm.com/index.php?rid=5575919&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213459%26dopt%3DAbstract Authors: Bonanni A, Ambrosi A, Pumera M Abstract There is immense demand for complex nanoarchitectures based on graphene nanostructures in the fields of biosensing or nanoelectronics. DNA molecules represent the most versatile and programmable recognition element and can provide a unique massive parallel assembly strategy with graphene nanomaterials. Here we demonstrate a facile strategy for covalent linking of single stranded DNA (ssDNA) to graphene using carbodiimide chemistry and apply it to genosensing. Since graphenes can be prepared by different methods and can contain various oxygen containing groups, we thoroughly investigated the utility of four different chemically modified graphenes for functionalization by ssDNA. The materials were characterized in detail and the differ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575919 Fri, 30 Dec 2011 05:00:00 +0100 5575919 http://www.medworm.com/index.php?rid=5575917&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213484%26dopt%3DAbstract Authors: Krokos E, Spänig F, Ruppert M, Hirsch A, Guldi DM Abstract A series of truly water-soluble C(60) /porphyrin electron donor-acceptor conjugates has been synthesized to serve as powerful mimics of photosynthetic reaction centers. To this end, the overall water-solubility of the conjugates was achieved by adding hydrophilic dendrimers of different generations to the porphyrin moiety. An important variable is the metal center of the porphyrin; we examined zinc(II), copper(II), cobalt(II), nickel(II), iron(III), and manganese(III). The first insights into electronic communication between the electron donors and the electron acceptors came from electrochemical assays, which clearly indicate that the redox processes centered either on C(60) or the porphyrins are mutually affecte... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575917 Fri, 30 Dec 2011 05:00:00 +0100 5575917 http://www.medworm.com/index.php?rid=5575913&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213563%26dopt%3DAbstract Authors: Schwizer D, Patton JT, Cutting B, Smieško M, Wagner B, Kato A, Weckerle C, Binder FP, Rabbani S, Schwardt O, Magnani JL, Ernst B Abstract A new class of N-acetyl-D-glucosamine (GlcNAc) mimics for E-selectin antagonists was designed and synthesized. The mimic consists of a cyclohexane ring substituted with alkyl substituents adjacent to the linking position of the fucose moiety. Incorporation into E-selectin antagonists led to the test compounds 8 and the 2'-benzoylated analogues 21, which exhibit affinities in the low micromolar range. By using saturation transfer difference (STD)-NMR it could be shown that the increase in affinity does not result from an additional hydrophobic contact of the alkyl substituent with the target protein E-selectin, but rather from a steric e... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575913 Fri, 30 Dec 2011 05:00:00 +0100 5575913 http://www.medworm.com/index.php?rid=5575912&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213570%26dopt%3DAbstract Authors: Kandoth N, Vittorino E, Sciortino MT, Parisi T, Colao I, Mazzaglia A, Sortino S Abstract We have developed a supramolecular nanoassembly capable of inducing remarkable levels of cancer cell mortality through a bimodal action based on the simultaneous photogeneration of nitric oxide (NO) and singlet oxygen ((1) O(2) ). This was achieved through the appropriate incorporation of an anionic porphyrin (as (1) O(2) photosensitizer) and of a tailored NO photodonor in different compartments of biocompatible nanoparticles based on cationic amphiphilic cyclodextrins. The combination of steady-state and time-resolved spectroscopic techniques showed the absence of significant intra- and interchromophoric interaction between the two photoactive centers embedded in the nanoparticles, wi... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575912 Fri, 30 Dec 2011 05:00:00 +0100 5575912 http://www.medworm.com/index.php?rid=5575954&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213022%26dopt%3DAbstract Authors: Chauvin T, Torres S, Rosseto R, Kotek J, Badet B, Durand P, Tóth E Abstract Enzyme-responsive MRI-contrast agents containing a "self-immolative" benzylcarbamate moiety that links the MRI-reporter lanthanide complex to a specific enzyme substrate have been developed. The enzymatic cleavage initiates an electronic cascade reaction that leads to a structural change in the Ln(III) complex, with a concomitant response in its MRI-contrast-enhancing properties. We synthesized and investigated a series of Gd(3+) and Yb(3+) complexes, including those bearing a self-immolative arm and a sugar unit as selective substrates for β-galactosidase; we synthesized complex LnL(1) , its NH(2) amine derivatives formed after enzymatic cleavage, LnL(2) , and two model compounds, LnL(3) and LnL... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575954 Wed, 28 Dec 2011 05:00:00 +0100 5575954 http://www.medworm.com/index.php?rid=5575953&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213028%26dopt%3DAbstract Authors: Gallina ME, Baytekin B, Schalley C, Ceroni P Abstract Two rotaxanes with benzyl ether axles and tetralactam wheels were synthesized through an anion template effect. They carry naphthalene chromophores attached to the stopper groups and a pyrene chromophore attached to the wheel. The difference between the two rotaxanes is represented by the connecting unit of the naphthyl chromophore to the rotaxane axle: a triazole or an alkynyl group. Both rotaxanes exhibit excellent light-harvesting properties: excitation of the naphthalene chromophores is followed by energy transfer to the pyrene unit with efficiency higher than 90 % in both cases. This represents an example of light-harvesting function among chromophores belonging to mechanically interlocked components, that is, th... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575953 Wed, 28 Dec 2011 05:00:00 +0100 5575953 http://www.medworm.com/index.php?rid=5575952&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213039%26dopt%3DAbstract Authors: Pignataro L, Boghi M, Civera M, Carboni S, Piarulli U, Gennari C Abstract A library of 19 binol-derived chiral monophosphites that contain a phthalic acid diamide group (PhthalaPhos) has been designed and synthesized in four steps. These new ligands were screened in the rhodium-catalyzed enantioselective hydrogenation of prochiral dehydroamino esters and enamides. Several members of the library showed excellent enantioselectivity with methyl 2-acetamido acrylate (6 ligands gave >97 % ee), methyl (Z)-2-acetamido cinnamate (6 ligands gave >94 % ee), and N-(1-phenylvinyl)acetamide (9 ligands gave >95 % ee), whilst only a few representatives afforded high enantioselectivities for challenging and industrially relevant substrates N-(3,4-dihydronaphthalen-1-yl)-ace... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575952 Wed, 28 Dec 2011 05:00:00 +0100 5575952 http://www.medworm.com/index.php?rid=5575951&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213052%26dopt%3DAbstract Authors: Wang HB, Mudraboyina BP, Wisner JA Abstract Two series of DDD and AAA hydrogen-bond arrays were synthesized that form triply-hydrogen-bonded double-helical complexes when combined in CDCl(3) solution. Derivatization of the DDD arrays with electron-withdrawing groups increases the complex association constants by up to a factor of 30 in those arrays examined. Derivatization of the AAA arrays with electron donating substituents reveals a similar magnitude effect on the complex stabilities. The effect of substitution on both types of arrays are modeled quite satisfactorily (R(2) > 0.96 in all cases) as free energy relationships with respect to the sums of their Hammett substituent constants. In all, the complex stabilities can be manipulated over more than three orders of ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575951 Wed, 28 Dec 2011 05:00:00 +0100 5575951 http://www.medworm.com/index.php?rid=5575938&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213135%26dopt%3DAbstract Authors: Tabata H, Wada N, Takada Y, Nakagomi J, Miike T, Shirahase H, Oshitari T, Takahashi H, Natsugari H Abstract Nitrogen chirality: Potent new ACAT inhibitors with seven-membered-ring benzolactams as the core structures were first prepared, and the axial chirality recognized by the enzyme was clarified (e.g., 1; see scheme). The chirality at the axis (aS) of 1 controls the conformation of the entire lactam ring, causing the N5-CH(3) to arrange in a pseudo-equatorial position (i.e., the amine at N5 is a chiral center with the S-configuration) both in the crystal state and in solution. PMID: 22213135 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575938 Wed, 28 Dec 2011 05:00:00 +0100 5575938 http://www.medworm.com/index.php?rid=5575911&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213584%26dopt%3DAbstract Synthesis and Characterization of Photoswitchable Fluorescent SiO(2) Nanoparticles. Chemistry. 2011 Dec 28; Authors: May F, Peter M, Hütten A, Prodi L, Mattay J Abstract Switchable fluorescent silica nanoparticles have been prepared by covalently incorporating a fluorophore and a photochromic compound inside the particle core. The fluorescence can be switched reversibly between an on- and off-state via energy transfer. The particles were synthesized using different amounts of the photoswitchable compound (spiropyran) and the fluorophore (rhodamine B) in a size distribution between 98 and 140 nm and were characterized in terms of size, switching properties, and fluorescence efficiency by TEM, and UV\Vis and fluorescence spectroscopy. PMID: 22213584 [PubMed - as supp... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575911 Wed, 28 Dec 2011 05:00:00 +0100 5575911 http://www.medworm.com/index.php?rid=5575941&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213091%26dopt%3DAbstract Authors: Gonzaga F, Grande JB, Brook MA Abstract Silicone surfactants are widely used in commerce because of the unusual surface activity when compared with fluorocarbon or hydrocarbon surfactants. However, most silicone surfactants are comprised of ill-defined mixtures, which preclude the development of an understanding of structure-surface activity relationships. Herein, we report a synthetic strategy that permits exquisite control over silicone structure by using the B(C(6) F(5) )(3) -catalyzed condensation of hydro- and alkoxysilanes. Six different, precise hydrophobes were then mated to hydrophilic poly(oxyethylene)s of three different molecular weights by a metal-free click cyclization to generate a library of explicit silicone surfactants. These compounds were calculated to ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575941 Tue, 27 Dec 2011 05:00:00 +0100 5575941 http://www.medworm.com/index.php?rid=5575939&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213119%26dopt%3DAbstract Authors: Kong KH, Tan CK, Lin X, Lam Y Abstract A thiouronium-based solid-phase synthesis of a 1,3,5-triazine scaffold has been developed. The key feature of the synthesis is the use of a readily accessible solid-supported thiouronium salt as a primary precursor for the stepwise assembly of the 1,3,5-triazine substrate. The sulfur linker employed in the synthesis is stable under both acidic and basic conditions and is versatile enough to provide access to monocyclic, bicyclic, and spirocyclic compounds with the 1,3,5-triazine scaffold. By using this synthetic strategy, a representative set of 79 compounds containing the 1,3,5-triazine scaffold were prepared. PMID: 22213119 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575939 Tue, 27 Dec 2011 05:00:00 +0100 5575939 http://www.medworm.com/index.php?rid=5575936&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213165%26dopt%3DAbstract Authors: Klapötke TM, Martin FA, Stierstorfer J Abstract 1,5-Diaminotetrazole can be nitrated under very mild conditions by using nitronium tetrafluoroborate to result in 5-amino-1-nitriminotetrazole (1) in good yields. The same reaction can be performed with 1-amino-5-amino-4-methyltetrazole to yield 5-amino-4-methyl-1-nitriminotetrazole (2). Both compounds have been isolated and completely characterized by using vibrational spectroscopy, mass spectrometry, and differential scanning calorimetry. Additionally, X-ray diffraction measurements of the neutral compounds could be obtained; they indicated the structure of both compounds to be zwitterionic. Compounds 1 and 2 exhibit extremely high sensitivities to impact and friction and high positive heats of formation of 496 (1) and 453... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575936 Tue, 27 Dec 2011 05:00:00 +0100 5575936 http://www.medworm.com/index.php?rid=5575932&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213251%26dopt%3DAbstract Formal Asymmetric Hydration of Non-Activated Alkenes in Aqueous Medium through a "Chemoenzymatic Catalytic System" Chemistry. 2011 Dec 27; Authors: Schnapperelle I, Hummel W, Gröger H Abstract A direct one-pot conversion of (substituted) styrene(s) into the corresponding (substituted) (R)-phenylethan-1-ol(s) in a highly enantioselective manner has been achieved by using a "chemoenzymatic catalytic system", comprising a palladium-catalyzed Wacker-Tsuji oxidation and subsequent enantioselective enzymatic reduction of the in situ-formed (substituted) acetophenone(s). PMID: 22213251 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575932 Tue, 27 Dec 2011 05:00:00 +0100 5575932 http://www.medworm.com/index.php?rid=5575920&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213439%26dopt%3DAbstract Authors: Yuan L, Lin W, Cao Z, Wang J, Chen B Abstract Dual-excitation ratiometric fluorescent probes allow the measurement of fluorescence intensities at two excitation wavelengths, which should provide a built-in correction for environmental effects. However, most of the small-molecule dual-excitation ratiometric probes that have been reported thus far have shown rather limited separation between the excitation wavelengths (20-70 nm) and/or a very small molar absorption coefficient at one of the excitation wavelengths. These shortcomings can lead to cross-excitation and thus to errors in the measurement of fluorescence intensities and ratios. Herein, we report a FRET-based molecular strategy for the construction of small-molecule dual-excitation ratiometric probes in which the ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575920 Tue, 27 Dec 2011 05:00:00 +0100 5575920 http://www.medworm.com/index.php?rid=5575910&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213590%26dopt%3DAbstract Authors: Hu C, Chen Y, Chen X, Zhang B, Yang J, Zhou J, Zhang MQ Abstract In this paper, the effect of the internal micro-magnetic field (IMMF) on the photocurrent property of conjugated polymer/inorganic semiconductor nanocomposites is reported and analyzed. By using the redox reaction, magnetic Fe(3) O(4) nanoparticles were coated on the surface of highly active nanorods of conjugated polyaniline (PANI), forming an internal micro-magnetic electron donor (i.e., Fe(3) O(4) @PANI). After subsequent incorporation of CdS nanoparticles (serving as electron acceptors), the power conversion efficiency (PCE) of the system (Fe(3) O(4) @PANI-CdS) was found to be as high as 3.563 %, contrasting sharply with the value (1.135 %) of the hybrid without Fe(3) O(4) (PANI-CdS). This obvious enh... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575910 Tue, 27 Dec 2011 05:00:00 +0100 5575910 http://www.medworm.com/index.php?rid=5575949&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213071%26dopt%3DAbstract Authors: Wang H, Kobayashi N, Jiang J Abstract Quintuple-decker sandwich: Homoleptic pentakis(2,3,9,10,16,17,23,24-octa(butyloxy)phthalocyaninato) lanthanide-cadmium quintuple-decker complexes were isolated and structurally characterized. They represent the first example of sandwich-type stacked tetrapyrrole-metal complexes with five decks (see figure; the tetrapyrrole molecules are represented by the blue/pink discs, TCB=1,2,4-trichlorobenzene). PMID: 22213071 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575949 Fri, 23 Dec 2011 05:00:00 +0100 5575949 http://www.medworm.com/index.php?rid=5575942&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213085%26dopt%3DAbstract In this report, we present clear evidence that the presence of nanographite impurities within carbon nanotubes (CNTs) is responsible for providing the previously reported enhanced electrochemical response. We have demonstrated this effect on homocysteine, N-acetyl-L-cysteine, nitric oxide, and insulin, which are important biological agents in the body. Moreover, we also showed that the influence of nanographite impurities on the electrochemistry of carbon nanotubes is prevalent among a variety of CNTs, such as single-walled CNTs, double-walled CNTs, and few-walled CNTs. Our findings will have a profound influence upon the biomedical applications of CNTs. PMID: 22213085 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575942 Fri, 23 Dec 2011 05:00:00 +0100 5575942 http://www.medworm.com/index.php?rid=5575940&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213109%26dopt%3DAbstract Authors: Zhang X, You L, Anslyn EV, Qian X Abstract Ginsenosides are complex natural products with a diverse array of biological activities, but their molecular recognition and sensing is challenging. A library of simple bis-boronic acid-based receptors with various spacers was synthesized for the sensing of ginsenosides. The incorporation of two boronic acids allowed the pairing of two indicators, which can simultaneously bind the receptors or two saccharides within the ginsenosides. A cross-reactive sensing array was therefore constructed using the receptors in conjunction with different pairs of indicators. LDA plots created from the colorimetric response of the hosts and indicator pairs reveal excellent classification of the ginsenosides, and the corresponding loading plots rev... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575940 Fri, 23 Dec 2011 05:00:00 +0100 5575940 http://www.medworm.com/index.php?rid=5575937&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213146%26dopt%3DAbstract Authors: Dielmann F, Schindler A, Scheuermayer S, Bai J, Merkle R, Zabel M, Virovets AV, Peresypkina EV, Brunklaus G, Eckert H, Scheer M Abstract Slow diffusion reactions of the pentaphosphaferrocene [Cp*Fe(η(5) -P(5) )] (Cp*=η(5) -C(5) Me(5) (1)) with CuX (X=Cl, Br, I) in different stoichiometric ratios and solvent mixtures result in the formation of one- and two-dimensional polymeric compounds 2-6 with molecular formula [{Cu(μ-X)}{Cp*Fe(μ(3) ,η(5) :η(1) :η(1) -P(5) )}](n) (X=Cl (2 a), I (2'c)), [{Cu(μ-I)}{Cp*Fe(μ(3) ,η(5) :η(1) :η(1) -P(5) )}](n) (3), [{CuX}{Cp*Fe(μ(4) ,η(5) :η(1) :η(1) :η(1) -P(5) )}](n) (X=Cl (4 a), Br (4 b), I (4 c), Br (4'b), I (4'c)), [{Cu(3) (μ-I)(2) (μ(3) -I)}{Cp*Fe(μ(5) ,η(5) :η(1) :η(1) :η(1) :η(1) -P(5) )}](n) (5) and [{... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575937 Fri, 23 Dec 2011 05:00:00 +0100 5575937 http://www.medworm.com/index.php?rid=5575934&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213207%26dopt%3DAbstract Elemental Distribution and Thermoelectric Properties of Layered Tellurides 39R-M(0.067) Sb(0.667) Te(0.266) (M=Ge, Sn). Chemistry. 2011 Dec 23; Authors: Schneider MN, Fahrnbauer F, Rosenthal T, Döblinger M, Stiewe C, Oeckler O Abstract The isostructural phases 39R-Ge(0.067) Sb(0.667) Te(0.266) (R3¯m, a=4.2649(1), c=75.061(2) Å) and 39R-Sn(0.067) Sb(0.667) Te(0.266) (R3¯m, a=4.2959(1), c=75.392(2) Å) were prepared by quenching stoichiometric melts of the pure elements and subsequent annealing at moderate temperatures. Their structures are comparable to "superlattices" synthesized by layer-by-layer deposition onto a substrate. These structures show no stacking disorder by electron microscopy. The structure of the metastable layered phases are similar to that of 39R-S... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575934 Fri, 23 Dec 2011 05:00:00 +0100 5575934 http://www.medworm.com/index.php?rid=5575928&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213333%26dopt%3DAbstract Authors: Dai FR, Zhan HM, Liu Q, Fu YY, Li JH, Wang QW, Xie Z, Wang L, Yan F, Wong WY Abstract Four new solution-processible small-molecular platinum(II)-bis(aryleneethynylene) complexes consisting of benzothiadiazole as the electron acceptor and triphenylamine and/or thiophene as the electron donor were conveniently synthesized and characterized by physicochemical and computational methods, and utilized as the electron-donor materials in the fabrication of solution-processed bulk heterojunction (BHJ) solar cells. The effect of different electron-donor groups in these small molecules on the optoelectronic and photovoltaic properties was also examined. The optical and time-dependent density functional theory studies showed that the incorporation of stronger electron-donor groups sig... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575928 Fri, 23 Dec 2011 05:00:00 +0100 5575928 http://www.medworm.com/index.php?rid=5575922&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213421%26dopt%3DAbstract Authors: Pan QJ, Odoh SO, Asaduzzaman AM, Schreckenbach G Abstract To model the structures of dissolved uranium contaminants adsorbed on mineral surfaces and further understand their interaction with geological surfaces in nature, we have performed periodic density funtional theory (DFT) calculations on the sorption of uranyl species onto the TiO(2) rutile (110) surface. Two kinds of surfaces, an ideal dry surface and a partially hydrated surface, were considered in this study. The uranyl dication was simulated as penta- or hexa-coordinated in the equatorial plane. Two bonds are contributed by surface bridging oxygen atoms and the remaining equatorial coordination is satisfied by H(2) O, OH(-) , and CO(3) (2-) ligands; this is known to be the most stable sorption structure. E... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575922 Fri, 23 Dec 2011 05:00:00 +0100 5575922 http://www.medworm.com/index.php?rid=5575916&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213523%26dopt%3DAbstract Authors: Klemm K, Radić Stojković M, Horvat G, Tomišić V, Piantanida I, Schmuck C Abstract Compounds 1-3, composed of two guanidiniocarbonylpyrrole moieties linked by oligoamide bridges and differing in number and type of basic groups, were prepared. The sites and degree of protonation of 1-3 depend strongly on the pH value. The interactions of these compounds with several double-stranded (ds) DNA and dsRNA were investigated by means of UV/Vis and CD spectroscopy as well as isothermal titration microcalorimetry (ITC). These studies revealed that the binding of 1-3 to the polynucleotides is driven by three factors, the presence of aliphatic amino groups, the protonation state of the compounds, and the steric properties of the polynucleotide binding site, that is, the shape and s... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575916 Fri, 23 Dec 2011 05:00:00 +0100 5575916 http://www.medworm.com/index.php?rid=5575915&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213538%26dopt%3DAbstract Authors: Feng G, Evangelisti L, Gasparini N, Caminati W Abstract The rotational spectra of six isotopologues (CF(3) (35) Cl⋅⋅⋅(14) NH(3) , CF(3) (37) Cl⋅⋅⋅(14) NH(3) , CF(3) (35) Cl⋅⋅⋅(15) NH(3) , CF(3) (37) Cl⋅⋅⋅(15) NH(3) , CF(3) (35) Cl⋅⋅⋅(14) ND(3) and CF(3) (37) Cl⋅⋅⋅(14) ND(3) ) of the CF(3) Cl⋅⋅⋅NH(3) adduct have been investigated and analyzed by pulsed jet Fourier transform microwave spectroscopy. Rotational, centrifugal distortion and quadrupole ((35) Cl, (37) Cl, (14) N) coupling constants have been precisely obtained. The two subunits of the complex are held together via a Cl⋅⋅⋅N halogen bond interaction. Information on the internal dynamics and on the dissociation energy of the complex i... Chemistry journals http://www.medworm.com/rss/comments.php?id=5575915 Fri, 23 Dec 2011 05:00:00 +0100 5575915 http://www.medworm.com/index.php?rid=5575914&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22213540%26dopt%3DAbstract Authors: Kochem A, Jarjayes O, Baptiste B, Philouze C, Vezin H, Tsukidate K, Tani F, Orio M, Shimazaki Y, Thomas F Abstract Where is the radical? The π-system of the diiminobenzene bridge adds a putative oxidation site to pro-phenoxyl copper(II) salophen complexes. It is shown that the bridge is effectively redox active and that the radical site (phenoxyl vs. diiminobenzene bridge) in the above cations is tuned by selective methoxy substitution. PMID: 22213540 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5575914 Fri, 23 Dec 2011 05:00:00 +0100 5575914 http://www.medworm.com/index.php?rid=5524829&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170220%26dopt%3DAbstract Comment on "A Nickel(II)-Based Radical-Ligand Complex as a Functional Model of Hydrogenase". Chemistry. 2011 Dec 23;17(52):15046-8 Authors: Stein M Abstract Where is the spin? Nickel bisthiolenes form paramagnetic monoanionic species. The non-innocence of the sulfur ligands makes a definite assignment of the oxidation state of the central metal atom difficult. EPR spectroscopy and DFT calculations reveal that there is an even distribution of unpaired spin between the nickel and each of the ligands (ca. 1/3 each). There is no evidence for a Ni(II) -based radical ligand complex as indicated in the original publication. PMID: 22170220 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524829 Thu, 22 Dec 2011 05:54:43 +0100 5524829 http://www.medworm.com/index.php?rid=5524828&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170259%26dopt%3DAbstract Response to Comment on "A Nickel(II)-Based Radical-Ligand Complex as a Functional Model of Hydrogenase". Chemistry. 2011 Dec 23;17(52):15049-50 Authors: Sarkar S Abstract Paramagnetic, monoanionic and square-planar nickel bisdithiolene complexes are best described as having delocalized class-III mixed-valent radical anionic ligands coordinated to a closed shell low-spin d(8) central metal, based on combined structural and spectroscopic studies given in several publications. They can be described by the resonance structures [Ni(II) (L(2-) )(L(-.) )](-) ↔ [Ni(II) (L(-.) )(L(2-) )](-) . In our formulation we have not differentiated the ligand "L", which can carry the charges 2- or 1-(.) and vice versa. PMID: 22170259 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524828 Thu, 22 Dec 2011 05:54:33 +0100 5524828 http://www.medworm.com/index.php?rid=5524766&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180338%26dopt%3DAbstract Authors: PMID: 22180338 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524766 Thu, 22 Dec 2011 05:48:35 +0100 5524766 http://www.medworm.com/index.php?rid=5524765&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180339%26dopt%3DAbstract Authors: PMID: 22180339 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524765 Thu, 22 Dec 2011 05:48:25 +0100 5524765 http://www.medworm.com/index.php?rid=5524763&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22184037%26dopt%3DAbstract Authors: Nun P, Egbert JD, Oliva-Madrid MJ, Nolan SP Abstract A pinch of gold will do: Alkenyl phosphates, useful substrates in many cross-coupling reactions, can be synthesized by gold-catalyzed hydrophosphoryloxylation of terminal alkynes. The use of [Au(IPr)(OH)] as a pre-catalyst in a silver-free protocol permits low catalyst loadings and yields excellent results in terms of selectivity toward the kinetic product. PMID: 22184037 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524763 Mon, 19 Dec 2011 05:00:00 +0100 5524763 http://www.medworm.com/index.php?rid=5524831&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170170%26dopt%3DAbstract Authors: PMID: 22170170 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524831 Fri, 16 Dec 2011 05:00:00 +0100 5524831 http://www.medworm.com/index.php?rid=5524830&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170171%26dopt%3DAbstract Authors: PMID: 22170171 [PubMed - in process] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524830 Fri, 16 Dec 2011 05:00:00 +0100 5524830 http://www.medworm.com/index.php?rid=5524783&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22179859%26dopt%3DAbstract Preparation and Catalytic Performances of a Molecularly Imprinted Ru-Complex Catalyst with an NH(2) Binding Site on a SiO(2) Surface. Chemistry. 2011 Dec 16; Authors: Yang Y, Weng Z, Muratsugu S, Ishiguro N, Ohkoshi SI, Tada M Abstract A catalyst surface with an active metal site, a shape-selective reaction space, and an NH(2) binding site for o-fluorobenzophenone was designed and prepared by the molecular imprinting of a supported metal complex on a SiO(2) surface. A ligand of a SiO(2) -supported Ru complex that has a similar shape to the product of o-fluorobenzophenone hydrogenation was used as a template. An NH(2) binding site for o-fluorobenzophenone was spatially arranged on the wall of a molecularly imprinted cavity with a similar shape to the template. The structures... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524783 Fri, 16 Dec 2011 05:00:00 +0100 5524783 http://www.medworm.com/index.php?rid=5524782&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22179925%26dopt%3DAbstract Authors: Karaki F, Kabasawa Y, Yanagimoto T, Umeda N, Firman , Urano Y, Nagano T, Otani Y, Ohwada T Abstract Although many organic/inorganic compounds that release nitric oxide (NO) upon photoirradiation (phototriggered caged-NOs) have been reported, their photoabsorption wavelengths mostly lie in the UV region, because XNO bonds (X=heteroatom and metal) generally have rather strong π-bond character. Thus, it is intrinsically difficult to generate organic compounds that release NO under visible light irradiation. Herein, the structures and properties of N-pyramidal nitrosamine derivatives of 7-azabicyclo[2.2.1]heptanes that release NO under visible light irradiation are described. Bathochromic shifts of the absorptions of these nitrosamines, attributed to HOMO (n)-LUMO (π*) tr... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524782 Fri, 16 Dec 2011 05:00:00 +0100 5524782 http://www.medworm.com/index.php?rid=5524774&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22179940%26dopt%3DAbstract Authors: Ohla S, Beyreiss R, Fritzsche S, Glaser P, Nagl S, Stockhausen K, Schneider C, Belder D Abstract High-throughput screening for optimal reaction conditions and the search for efficient catalysts is of eminent importance in the development of chemical processes and for expanding the spectrum of synthetic methodologies in chemistry. In this context we report a novel approach for a microfluidic chemical laboratory integrating organic synthesis, separation and time-resolved fluorescence detection on a single microchip. The feasibility of our integrated laboratory is demonstrated by monitoring the formation of tetrahydroisoquinoline derivatives by Pictet-Spengler condensation. After on-chip reaction the products and residual starting material were separated enantioselectively on... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524774 Fri, 16 Dec 2011 05:00:00 +0100 5524774 http://www.medworm.com/index.php?rid=5524773&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22179970%26dopt%3DAbstract Authors: Tsuchiya Y, Shiraki T, Matsumoto T, Sugikawa K, Sada K, Yamano A, Shinkai S Abstract In Nature, chromophoric groups play various roles, such as oxygen carriers, electron donors, light sensitizers, which are achieved in many cases by control of their aggregation modes in proteins. Host-guest chemistry between cyclodextrins and porphyrins has attracted great interest from supramolecular chemists because of their unique structures and functions that mimic those of proteins with chromophoric prosthetic groups. To mimic Nature's contrivances, the host-guest systems between cyclodextrins and porphyrins have frequently been studied. It is really surprising, however, that to date no detailed structural information of these complexes has been obtained from single-crystal analysis. ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524773 Fri, 16 Dec 2011 05:00:00 +0100 5524773 http://www.medworm.com/index.php?rid=5524772&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22179991%26dopt%3DAbstract Authors: Gaeta C, Talotta C, Farina F, Campi G, Camalli M, Neri P Abstract The shaping of a calix[7]arene macrocycle into cone-like structure 3, through exhaustive alkylation of doubly bridged calix[7]arene derivative 2 with bulky groups, has been investigated. Conformational details about the structure adopted by calix[7]arene derivative 3 in solution have been obtained by using chemical shift surface maps, as previously reported by our group. Thus, chemical shift contour plots indicated that 3 adopted a cone-shaped structure in solution analogous to that adopted by the known p-tert-butylcalix[7]arene heptacarboxylic acid derivative 4. Interestingly, the X-ray structure of derivative 3 showed a high degree of similarity to the theoretical structure, which confirmed the validity of... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524772 Fri, 16 Dec 2011 05:00:00 +0100 5524772 http://www.medworm.com/index.php?rid=5524771&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180016%26dopt%3DAbstract Authors: Rouquet G, Robert F, Méreau R, Castet F, Renaud P, Landais Y Abstract Various silylboranes, which were outfitted with a catecholborane moiety at one end and a (Me(3) Si)(3) Si moiety at the other end of a carbon chain, were prepared through the hydroboration of the corresponding unsaturated silanes. The C-centered radical species generated from these silylboranes efficiently cyclized to provide, through a 5-exo intramolecular homolytic substitution at the silicon center, the corresponding silacycle and a Me(3) Si radical that was subsequently trapped by sulfonyl acceptors. These cyclizations proceeded at unprecedented rates, due, in part, to a strong gem-dialkyl effect that was attributable to the presence of bulky substituents on a quaternary center located on the chain.... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524771 Fri, 16 Dec 2011 05:00:00 +0100 5524771 http://www.medworm.com/index.php?rid=5524770&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180030%26dopt%3DAbstract Authors: Maiti M, Siegmund V, Abramov M, Lescrinier E, Rosemeyer H, Froeyen M, Ramaswamy A, Ceulemans A, Marx A, Herdewijn P Abstract Orthogonal nucleic acids are chemically modified nucleic acid polymers that are unable to transfer information with natural nucleic acids and thus can be used in synthetic biology to store and transfer genetic information independently. Recently, it was proposed that xylose-DNA (dXNA) can be considered to be a potential candidate for an orthogonal system. Herein, we present the structure in solution and conformational analysis of two self-complementary, fully modified dXNA oligonucleotides, as determined by CD and NMR spectroscopy. These studies are the initial experimental proof of the structural orthogonality of dXNAs. In aqueous solution, dXNA dup... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524770 Fri, 16 Dec 2011 05:00:00 +0100 5524770 http://www.medworm.com/index.php?rid=5524769&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180064%26dopt%3DAbstract In this study we used a FRET pair labeled Hg(II) binding DNA and monitored metal-induced folding in the presence of various cations. While nonspecific electrostatically mediated folding can be very significant, at each tested salt condition, Hg(II) induced folding was still observed with a similar sensitivity. We also studied the biophysical meaning of the acceptor/donor fluorescence ratio that allowed us to explain the experimental observations. Potential solutions for this ionic strength problem have been discussed. For example, probes designed to signal the formation of double-stranded DNA showed a lower dependency on ionic strength. PMID: 22180064 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524769 Fri, 16 Dec 2011 05:00:00 +0100 5524769 http://www.medworm.com/index.php?rid=5524768&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180095%26dopt%3DAbstract Authors: Jankiewicz BJ, Vinueza NR, Reece JN, Lee YC, Williams P, Nash JJ, Kenttämaa HI Abstract The reactivity of 3-hydroxy-2,4,6-tridehydropyridinium cation was found to be drastically different from the reactivity of 2,4,6-tridehydropyridinium cation. While the latter triradical reacts with tetrahydrofuran, dimethyl disulfide and ally iodide via three consecutive atom or group abstractions, the former triradical exhibits this behavior only with tetrahydrofuran. Only a single atom or group abstraction was observed for the 3-hydroxy-2,4,6-tridehydropyridinium cation upon interaction with dimethyl disulfide and allyl iodide. This change in reactivity is caused by the hydroxyl group that strengthens the interactions between the two radical sites adjacent to it, thus reducing their ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524768 Fri, 16 Dec 2011 05:00:00 +0100 5524768 http://www.medworm.com/index.php?rid=5524767&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22180129%26dopt%3DAbstract Authors: Hoi KH, Organ MG Abstract This base is just right! A new base, potassium 2,2,5,7,8-pentamethylchroman-6-oxide, for Pd-catalysed amination has been rationally designed that has sufficient basicity to efficiently deprotonate the intermediate aryl palladium ammonium complex, leading to far better rates than obtained with carbonate, which is known to be very mild. At the same time, this new base possesses minimal nucleophilicity to mitigate the degradation of base-sensitive functional groups in the starting materials and products, such as is commonly seen with potassium or sodium tert-butoxide. PMID: 22180129 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524767 Fri, 16 Dec 2011 05:00:00 +0100 5524767 http://www.medworm.com/index.php?rid=5524787&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22173724%26dopt%3DAbstract Authors: Maiti M, Michielssens S, Dyubankova N, Maiti M, Lescrinier E, Ceulemans A, Herdewijn P Abstract Nucleoside phosphoramidates (NPs) are a class of nucleotide analogues that has been developed as potential antiviral/antitumor prodrugs. Recently, we have shown that some amino acid nucleoside phosphoramidates (aaNPs) can act as substrates for viral polymerases like HIV-1 RT. Herein, we report the synthesis and hydrolysis of a series of new aaNPs, containing either natural or modified nucleobases to define the basis for their differential reactivity. Aqueous stability, kinetics, and hydrolysis pathways were studied by NMR spectroscopy at different solution pD values (5-7) and temperatures. It was observed that the kinetics and mechanism (PN and/or PO bond cleavage) of th... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524787 Thu, 15 Dec 2011 05:00:00 +0100 5524787 http://www.medworm.com/index.php?rid=5524823&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170289%26dopt%3DAbstract Authors: Taft F, Harmrolfs K, Nickeleit I, Heutling A, Kiene M, Malek N, Sasse F, Kirschning A Abstract Access of four new tumor specific folic acid/ansamitocin conjugates is reported that relies on a synthetic strategy based on the combination of mutasynthesis and semisynthesis. Two bromo-ansamitocin derivatives were prepared by mutasynthesis or by a modified fermentation protocol, respectively, that served as starting point for the semisynthetic introduction of an allyl amine linker under Stille conditions. A sequence of standard coupling steps introduced the pteroic acid/glutamic acid/cysteine unit to the modified ansamitocins. All new derivatives, including those that are expected to be generated after internalization of the folic acid/ansamitocin conjugates into the cancer cel... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524823 Wed, 14 Dec 2011 05:00:00 +0100 5524823 http://www.medworm.com/index.php?rid=5524819&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170304%26dopt%3DAbstract Authors: Kopylovich MN, Karabach YY, Guedes da Silva MF, Figiel PJ, Lasri J, Pombeiro AJ Abstract Template combination of copper acetate (Cu(AcO)(2) ⋅H(2) O) with sodium dicyanamide (NaN(C≡N)(2) , 2 equiv) or cyanoguanidine (N≡CNHC(=NH)NH(2) , 2 equiv) and an alcohol ROH (used also as solvent) leads to the neutral copper(II)-(2,4-alkoxy-1,3,5-triazapentadienato) complexes [Cu{NHC(OR)NC(OR)NH}(2) ] (R=Me (1), Et (2), nPr (3), iPr (4), CH(2) CH(2) OCH(3) (5)) or cationic copper(II)-(2-alkoxy-4-amino-1,3,5-triazapentadiene) complexes [Cu{NHC(OR)NHC(NH(2) )NH}(2) ](AcO)(2) (R=Me (6), Et (7), nPr (8), nBu (9), CH(2) CH(2) OCH(3) (10)), respectively. Several intermediates of this reaction were isolated and a pathway was proposed. The deprotonation of 6-10 with NaOH al... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524819 Wed, 14 Dec 2011 05:00:00 +0100 5524819 http://www.medworm.com/index.php?rid=5524818&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170325%26dopt%3DAbstract Authors: Kui SC, Hung FF, Lai SL, Yuen MY, Kwok CC, Low KH, Chui SS, Che CM Abstract A series of [(R'-C^N^C-R'')Pt(L)] complexes with doubly deprotonated cyclometalated R'-C^N^C-R'' ligands (R'-C^N^C-R''=2,6-diphenylpyridine derivatives) functionalized with carbazole, fluorene, or thiophene unit(s) have been synthesized and their photophysical properties studied. The X-ray crystal structures reveal extensive intermolecular π⋅⋅⋅π and CH⋅⋅⋅π interactions between the cyclometalated C^N^C ligands. Compared to previously reported cyclometalated platinum(II) complexes [(C^N^C)Pt(L)], which are non-emissive in solution at room temperature, the carbazole-, fluorene- and thiophene-functionalized [(R'-C^N^C-R'')Pt(L)] (L=DMSO 1-9, CNAr, 1 a-9 a) complexes are emis... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524818 Wed, 14 Dec 2011 05:00:00 +0100 5524818 http://www.medworm.com/index.php?rid=5524815&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170350%26dopt%3DAbstract Authors: Li J, Yoshizawa K Abstract The pathway for the cleavage of an aromatic CC bond in quinoxaline by a tungsten(II) complex [W(PMe(3) )(4) (η(2) -CH(2) PMe(2) )H] is explored by performing detailed DFT calculations. The real active complex was found to be [W(PMe(3) )(2) (η(2) -CH(2) PMe(2) )H] rather than [W(PMe(3) )(4) ]. The key step in the whole reaction is the reductive elimination of two hydrides that are located originally on quinoxaline. PMID: 22170350 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524815 Wed, 14 Dec 2011 05:00:00 +0100 5524815 http://www.medworm.com/index.php?rid=5524814&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170388%26dopt%3DAbstract Authors: Ding M, Wang B, Wang Z, Zhang J, Fuhr O, Fenske D, Gao S Abstract A single-chain magnet (SCM) was constructed from manganese(III) 5,10,15-tris(pentafluorophenyl)corrole complex [Mn(III) (tpfc)] through supramolecular π-π stacking without bridging ligands. In the crystal structures, [Mn(tpfc)] molecules crystallized from different solvents, such as methanol, ethyl acetate, and ethanol, exhibit different molecular orientations and intermolecular π-π interaction or weak Mn⋅⋅⋅O interaction to form a supramolecular one-dimensional motif or dimer. These three complexes show very different magnetic behaviors at low temperature. Methanol solvate 1 shows obvious frequency dependence of out-of-phase alternating-current magnetic susceptibility below 2 K and a magnetizatio... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524814 Wed, 14 Dec 2011 05:00:00 +0100 5524814 http://www.medworm.com/index.php?rid=5524813&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170418%26dopt%3DAbstract Authors: Pubill-Ulldemolins C, Bonet A, Bo C, Gulyás H, Fernández E Abstract Bases play an important role in organocatalytic boron conjugate addition reactions. The sole use of MeOH and a base can efficiently transform acyclic and cyclic activated olefins into the corresponding β-borated products in the presence of diboron reagents. Inorganic and organic bases deprotonate MeOH in the presence of diboron reagents. It is concluded, on the basis of theoretical calculations, NMR spectroscopic data, and ESI-MS experiments, that the methoxide anion forms a Lewis acid-base adduct with the diboron reagent. The sp(2) B atom of the methoxide-diboron adduct gains a strongly nucleophilic character, and attacks the electron-deficient olefin. The methanol protonates the intermediate, generati... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524813 Wed, 14 Dec 2011 05:00:00 +0100 5524813 http://www.medworm.com/index.php?rid=5524812&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170459%26dopt%3DAbstract Authors: Fernandes A, Hensenne P, Mathy B, Guo W, Nysten B, Jonas AM, Riant O Abstract Catalytic surfaces have been prepared by complexation of palladium on self-assembled terpyridine monolayers on silicon. A reaction-based fluorogenic probe was developed to allow facile visualization of the catalytic potential of the surface. Superior activity of the immobilized-catalyst compared with the homogeneous control reactions is demonstrated. PMID: 22170459 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524812 Wed, 14 Dec 2011 05:00:00 +0100 5524812 http://www.medworm.com/index.php?rid=5524811&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170494%26dopt%3DAbstract In this study, the TSC was detected and analyzed for the more common (1) H(1) H coupling as well. In synthesized model molecules the hydrogen positions could be well controlled. For several coupling constants the through-space mechanism was even found to be the predominant factor. The nature and magnitude of the phenomenon were also analyzed by density functional computations. Calculated carbon- and hydrogen-coupling maps and perturbed electronic densities suggest that the aromatic system strongly participates in the noncovalent contribution. Unlike covalent coupling, which is usually governed by the Fermi contact, TSC is dominated by the diamagnetic term comprising interactions of nuclei with the electron orbital angular momentum. The computations further revealed a strong distance and... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524811 Wed, 14 Dec 2011 05:00:00 +0100 5524811 http://www.medworm.com/index.php?rid=5524807&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170585%26dopt%3DAbstract Authors: Fenske T, Korth HG, Mohr A, Schmuck C Abstract Supramolecular nanoassemblies are gaining increasing importance as promising new materials with considerable potential for novel and promising applications. Within supramolecular nanoassemblies the connectivity of the monomeric units is based on reversible noncovalent interactions, like van der Waals interactions, hydrogen bonding, or ionic interactions. As the strength of these interactions depends on the molecular surrounding, the formation of nanoassemblies in principle can be controlled externally by changing the environment and/or the molecular shape of the underlying monomer. This way it is not only possible to switch the self-assembly on or off, but also to change between different aggregation states. In this minireview... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524807 Wed, 14 Dec 2011 05:00:00 +0100 5524807 http://www.medworm.com/index.php?rid=5524805&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170624%26dopt%3DAbstract Authors: Manna J, Rana RK Abstract Herein, we report a bottom-up, mineralization strategy, which borrows key principles from biomineralization processes, to synthesize nanostructured materials. A long-chain polyamine simultaneously mineralizes and assembles ZnO nanoparticles directly from water-soluble zinc salts under sustainable synthesis conditions. These thus-generated oriented structures undergo interesting morphogenesis that is controlled by changing the ratio of polyamine/Zn(2+) ions. As the ratio increases, the morphology changes from a spherical shape to oval-, dumbbell-, and finally hexagonal-rod-shaped structures that contain unique hollow rod structures. Using XPS, XRD, FT-IR, Raman spectroscopy, DLS, and confocal fluorescence microscopic analysis, we elucidate the mech... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524805 Wed, 14 Dec 2011 05:00:00 +0100 5524805 http://www.medworm.com/index.php?rid=5524804&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170626%26dopt%3DAbstract Authors: Vergote T, Nahra F, Welle A, Luhmer M, Wouters J, Mager N, Riant O, Leyssens T Abstract To be or not to bifluoride: Two synthetic pathways to unprecedented N-heterocyclic carbene copper(I) bifluoride complexes have been developed. Catalytic tests demonstrated that copper(I) bifluorides are very efficient catalysts, which do not require any additional activating agent. The first Cu-catalyzed diastereoselective allylation of (R)-N-tert-butanesulfinyl aldimines was also established. The method enables efficient, simple and general synthesis of enantiomerically enriched homoallylic amines at room temperatures in high yields. PMID: 22170626 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524804 Wed, 14 Dec 2011 05:00:00 +0100 5524804 http://www.medworm.com/index.php?rid=5524803&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170697%26dopt%3DAbstract Authors: Qian XF, Li B, Hu YY, Niu GX, Zhang DY, Che RC, Tang Y, Su DS, Asiri AM, Zhao DY Abstract A series of core-shell-structured composite molecular sieves comprising zeolite single crystals (i.e., ZSM-5) as a core and ordered mesoporous silica as a shell were synthesized by means of a surfactant-directed sol-gel process in basic medium by using cetyltrimethylammonium bromide (CTAB) as a template and tetraethylorthosilicate (TEOS) as silica precursor. Through this coating method, uniform mesoporous silica shells closely grow around the anisotropic zeolite single crystals, the shell thickness of which can easily be tuned in the range of 15-100 nm by changing the ratio of TEOS/zeolite. The obtained composite molecular sieves have compact meso-/micropore junctions that form a hi... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524803 Wed, 14 Dec 2011 05:00:00 +0100 5524803 http://www.medworm.com/index.php?rid=5524802&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170699%26dopt%3DAbstract Authors: Zhang Y, Parrish DA, Shreeve JN Abstract 4-Nitramino-3,5-dinitropyrazole was prepared and stabilized through the formation of its ammonium salt. With selected cations, 14 nitrogen-rich energetic salts were synthesized in high yield by metathesis reactions. These salts were fully characterized by (1) H, (13) C NMR, and IR spectroscopy and elemental analysis. Additionally, the structures of the ammonium, 3,4,5-triaminotriazolium, and biguanidinium salts were confirmed by single-crystal X-ray diffraction. Based on experimental and calculated values, the 4-nitramino-3,5-dinitropyrazolate salts show properties, such as decomposition temperatures (115-229 °C), detonation pressures (23.27-37.42 GPa) and velocities (7713-9013 ms(-1) ), and impact sensitivities (5-40 J... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524802 Wed, 14 Dec 2011 05:00:00 +0100 5524802 http://www.medworm.com/index.php?rid=5524801&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170731%26dopt%3DAbstract Authors: Schneider MW, Oppel IM, Ott H, Lechner LG, Hauswald HJ, Stoll R, Mastalerz M Abstract The synthesis of various periphery-substituted shape-persistent cage compounds by twelve-fold condensation reactions of four triptycene triamines and six salicyldialdehydes is described, where the substituents systematically vary in bulkiness. The resulting cage compounds were studied as permanent porous material by nitrogen sorption measurements. When the material is amorphous, the steric demand of the cages exterior does not strongly influence the gas uptake, resulting in BET surface areas of approximately 700 m(2)  g(-1) for all cage compounds 3 c-e, independently of the substituents bulkiness. In the crystalline state, materials of the same compounds show a strong interconnectio... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524801 Wed, 14 Dec 2011 05:00:00 +0100 5524801 http://www.medworm.com/index.php?rid=5524798&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170740%26dopt%3DAbstract Authors: Dai Y, Wu F, Zang Z, You H, Gong H Abstract Game of two electrophiles: Two partially positively charged sp(3) carbon atoms can be connected by using a catalytic Ni species in the presence of an environmentally benign Zn reductant, delivering allylated alkanes. This unprecedented approach allowed a variety of unactivated alkyl halides and substituted allylic carbonates to regioselectively afford E-alkenes in good to excellent yields. PMID: 22170740 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524798 Wed, 14 Dec 2011 05:00:00 +0100 5524798 http://www.medworm.com/index.php?rid=5524795&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170757%26dopt%3DAbstract Asymmetric Binary-Acid Catalysis with InBr(3) in the Inverse-Electron-Demanding Hetero-Diels-Alder Reaction of Mono- and Bis-Substituted Cyclopentadienes: Remote Fluoro-Effect on Stereocontrol. Chemistry. 2011 Dec 14; Authors: Lv J, Zhang L, Hu S, Cheng JP, Luo S Abstract Remote F effect: Unprecedented hetero-Diels-Alder reactions of mono- and bis-substituted cyclopentadienes have been realized by an asymmetric binary-acid catalyst that synergistically combines a chiral phosphoric acid 1 h/InBr(3) with good periselectivity, high regioselectivity, and excellent stereoselectivity. Substituent mapping of the chiral phosphoric acid indicates a dramatic remote ortho-fluoro effect on the stereocontrol. PMID: 22170757 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524795 Wed, 14 Dec 2011 05:00:00 +0100 5524795 http://www.medworm.com/index.php?rid=5524794&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170766%26dopt%3DAbstract Authors: Gensch T, Rönnefahrt M, Czerwonka R, Jäger A, Kataeva O, Bauer I, Knölker HJ Abstract Pd(II) caught in the act: The diaryl Pd(II) intermediate of a Pd(II) -catalyzed oxidative biaryl bond formation proceeding via a double CH bond activation has been isolated and fully characterized, including an X-ray crystal structure analysis. Stabilization due to chelation by adjacent pivaloyloxy and acetyl groups has allowed the isolation of this long-sought crucial intermediate. On gentle warming, the complex is transformed to a carbazole product, and the catalytically active Pd(II) species is regenerated by oxidation with Cu(II) . PMID: 22170766 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524794 Wed, 14 Dec 2011 05:00:00 +0100 5524794 http://www.medworm.com/index.php?rid=5524810&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170498%26dopt%3DAbstract Authors: Bao R, Zhang C, Wang Z, Zhang X, Ou X, Lee CS, Jie J, Zhang X Abstract Organic one-dimensional nanostructures are attractive building blocks for electronic, optoelectronic, and photonic applications. Achieving aligned organic nanowire arrays that can be patterned on a surface with well-controlled spatial arrangement is highly desirable in the fabrication of high-performance organic devices. We demonstrate a facile one-step method for large-scale controllable patterning growth of ordered single-crystal C(60) nanowires through evaporation-induced self-assembly. The patterning geometry of the nanowire arrays can be tuned by the shape of the covering hats of the confined curve-on-flat geometry. The formation of the pattern arrays is driven by a simple solvent evaporation proce... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524810 Tue, 13 Dec 2011 05:00:00 +0100 5524810 http://www.medworm.com/index.php?rid=5524809&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170534%26dopt%3DAbstract Authors: Möller HM, Baier MC, Mecking S, Talsi EP, Bryliakov KP Abstract To characterize the origin of living polymerization with nonmetallocene titanium-based catalysts containing o-fluoroaryl substituents, ethene polymerization by an o-fluorinated bis(enolatoimine) titanium catalyst and its nonfluorinated counterpart has been studied by multinuclear NMR spectroscopy by using methylaluminoxane (MAO) or AlMe(3) /CPh(3) B(C(6) F(5) )(4) as activators. Formation of ion pairs of the type [TiL(2) Me][MeMAO] and [TiL(2) Me][B(C(6) F(5) )(4) ] has been observed for both catalysts. These ion pairs react with ethene to afford the chain-propagating species [TiL(2) P][MeMAO] and [TiL(2) P][B(C(6) F(5) )(4) ], respectively (P=growing polymeryl chain). For the o-F-substituted catalyst species... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524809 Tue, 13 Dec 2011 05:00:00 +0100 5524809 http://www.medworm.com/index.php?rid=5524808&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170565%26dopt%3DAbstract Authors: Lee JH, Kang S, Jaworski J, Kwon KY, Seo ML, Lee JY, Jung JH Abstract GO MOFs! Azobenzoic-acid-functionalized graphene (A-GO) can act as a structure-directing template that influences hydrogel formation together with metal-organic frameworks (MOFs). Zn(2+) MOFs of pyridine derivatives work as framework linkers between the A-GO sheets (MOF-A-GO, see figure). MOF-A-GO exhibits a strong fluorescence enhancement upon gel formation. In addition, MOF-A-GO selectively recognizes trinitrotoluene. PMID: 22170565 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524808 Tue, 13 Dec 2011 05:00:00 +0100 5524808 http://www.medworm.com/index.php?rid=5524806&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170590%26dopt%3DAbstract Authors: Yin AX, Min XQ, Zhu W, Liu WC, Zhang YW, Yan CH Abstract PtCu nanostructures: PtCu nanocubes (NCs), concave nanocubes (CNCs), and PtPdCu CNCs with high-index facets (HIFs) were prepared through progressive galvanic replacements in a one-pot hydrothermal approach. The HIFs-enclosed CNCs showed superior activities to (100)-enclosed NCs catalyst for methanol oxidations owing to the modifications of both the surface electronic structures and the surface atomic arrangements. PMID: 22170590 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5524806 Tue, 13 Dec 2011 05:00:00 +0100 5524806 http://www.medworm.com/index.php?rid=5524796&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22170751%26dopt%3DAbstract Authors: Schindler A, Heindl C, Balázs G, Gröger C, Virovets AV, Peresypkina EV, Scheer M Abstract Treatment of the pentaphosphaferrocene [Cp*Fe(η(5) -P(5) )] with Cu(I) halides in the presence of different templates leads to novel fullerene-like spherical molecules that serve as hosts for the templates. If ferrocene is used as the template the 80-vertex ball [Cp(2) Fe]@[{Cp*Fe(η(5) -P(5) )}(12) {CuCl}(20) ] (4), with an overall icosahedral C(80) topological symmetry, is obtained. This result shows the ability of ferrocene to compete successfully with the internal template of the reaction system [Cp*Fe(η(5) -P(5) )], although the 90-vertex ball [{Cp*Fe(η(5) :η(1) :η(1) :η(1) :η(1) :η(1) -P(5) )}(12) (CuCl)(10) (Cu(2) Cl(3) )(5) {Cu(CH(3) CN)(2) }(5) ] (2 a) containing ... Chemistry journals http://www.medworm.com/rss/comments.php?id=5524796 Tue, 13 Dec 2011 05:00:00 +0100 5524796 http://www.medworm.com/index.php?rid=5505900&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161727%26dopt%3DAbstract Authors: Beier MJ, Kleist W, Wharmby MT, Kissner R, Kimmerle B, Wright PA, Grunwaldt JD, Baiker A Abstract A Co-based metal-organic framework (MOF) was investigated as a catalytic material in the aerobic epoxidation of olefins in DMF and exhibited, based on catalyst mass, a remarkably high catalytic activity compared with the Co-doped zeolite catalysts that are typically used in this reaction. The structure of STA-12(Co) is similar to that of STA-12(Ni), as shown by XRD Rietveld refinement and is stable up to 270 °C. For the epoxidation reaction, significantly different selectivities were obtained depending on the substrate. Although styrene was epoxidized with low selectivity due to oligomerization, (E)-stilbene was converted with high selectivities between 80 and 90 %. Leach... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505900 Mon, 12 Dec 2011 05:00:00 +0100 5505900 http://www.medworm.com/index.php?rid=5505899&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161767%26dopt%3DAbstract Authors: Gosiewska S, Raskatov JA, Shintani R, Hayashi T, Brown JM Abstract Chiral diene ligands: Conjugate addition of aryl boronic acids to cyclohexenone is catalysed by Rh complexes of the simple chiral diene (S)-bicyclo[3.3.1]nona-2,6-diene in unexpectedly high ee. Insight into the reasons, and more generally the TS structure and pathways with other catalysts, was explored by using density functional theory. There was a gratifyingly good agreement between calculation and experiment. A lack of obvious steric discrimination together with systematic variations in TS structure implicated stereoelectronics. PMID: 22161767 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505899 Mon, 12 Dec 2011 05:00:00 +0100 5505899 http://www.medworm.com/index.php?rid=5505898&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161774%26dopt%3DAbstract Authors: Argyo C, Cauda V, Engelke H, Rädler J, Bein G, Bein T Abstract Blood ties: We have designed a novel nanoscale, injectable drug-delivery system that combines heparin, which prevents blood clotting, with multifunctional core-shell colloidal mesoporous silica nanoparticles. The anticoagulant and biocompatible properties of heparin together with the highly porous features of the nanoparticles lead to an efficient multifunctional drug-delivery system that can itself act as an anticoagulant and allows for incorporation of biologically active molecules as deliverable cargo. PMID: 22161774 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505898 Mon, 12 Dec 2011 05:00:00 +0100 5505898 http://www.medworm.com/index.php?rid=5505897&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161804%26dopt%3DAbstract Authors: Erős G, Nagy K, Mehdi H, Pápai I, Nagy P, Király P, Tárkányi G, Soós T Abstract Catalytic hydrogenation that utilizes frustrated Lewis pair (FLP) catalysts is a subject of growing interest because such catalysts offer a unique opportunity for the development of transition-metal-free hydrogenations. The aim of our recent efforts is to further increase the functional-group tolerance and chemoselectivity of FLP catalysts by means of size-exclusion catalyst design. Given that hydrogen molecule is the smallest molecule, our modified Lewis acids feature a highly shielded boron center that still allows the cleavage of the hydrogen but avoids undesirable FLP reactivity by simple physical constraint. As a result, greater latitude in substrate scope can be achieved, as exempli... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505897 Mon, 12 Dec 2011 05:00:00 +0100 5505897 http://www.medworm.com/index.php?rid=5505895&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161811%26dopt%3DAbstract Authors: Ortiz RP, Herrera H, Seoane C, Segura JL, Facchetti A, Marks TJ Abstract Herein, we report a new family of naphthaleneamidinemonoimide-fused oligothiophene semiconductors designed for facile charge transport in organic field-effect transistors (OFETs). These molecules have planar skeletons that induce high degrees of crystallinity and hence good charge-transport properties. By modulating the length of the oligothiophene fragment, the majority carrier charge transport can be switched from n-type to ambipolar behavior. The highest FET performance is achieved for solution-processed films of 10-[(2,2'-bithiophen)-5-yl]-2-octylbenzo[lmn]thieno[3',4':4,5]imidazo[2,1-b][3,8]phenanthroline-1,3,6(2 H)-trione (NDI-3 Tp), with optimized film mobilities of 2×10(-2) and 0.7×10(-2... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505895 Mon, 12 Dec 2011 05:00:00 +0100 5505895 http://www.medworm.com/index.php?rid=5505894&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161822%26dopt%3DAbstract Authors: Chen S, Chen W, Shi W, Ma H Abstract Ferrocence and its derivatives have long been known to be a class of stable organometallic compounds, and their dissociation usually occurs under harsh conditions. Here we report a new type of ferrocene derivatives, 4,4-difluoro-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene and 4,4-difluoro-2,6-diethyl-8-ferrocenyl-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene, which surprisingly can hydrolyze under mild conditions. These two derivatives, initially developed as donor-acceptor probes for reactive oxygen species by incorporating the electron donor of ferrocene as a quencher into the fluorophore of BODIPY (boron dipyrromethene difluoride), barely emit fluorescence. Upon reaction with H(2) O under the irradiation of nat... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505894 Mon, 12 Dec 2011 05:00:00 +0100 5505894 http://www.medworm.com/index.php?rid=5505892&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161868%26dopt%3DAbstract Photoluminescence Emission and Photoinduced Hydrogen Production Driven by Pt(II) Pyridyl Complexes Anchored onto Mesoporous Silica. Chemistry. 2011 Dec 12; Authors: Mori K, Watanabe K, Fuku K, Yamashita H Abstract Photocatalytic H(2) evolution: The anchored Pt(II) terpyridine complexes, which are closely situated to each other within the mesoporous channels, exhibit unique photoluminescence properties and behave as single-component bifunctional photocatalysts that enable both visible-light sensitization and H(2) evolution without the need for an additional electron relay. PMID: 22161868 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505892 Mon, 12 Dec 2011 05:00:00 +0100 5505892 http://www.medworm.com/index.php?rid=5505890&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161936%26dopt%3DAbstract Authors: Duric S, Schmidt BM, Ninnemann NM, Lentz D, Tzschucke CC Abstract Fluor-ing it: The stable, crystalline trimethoxy(trifluorovinyl)borate is a convenient reagent for efficiently displacing a bromine atom with a trifluorovinyl group. This Suzuki coupling reaction significantly simplifies the route to trifluorostyrenes, which might be interesting compounds for materials science or medicinal chemistry. PMID: 22161936 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505890 Mon, 12 Dec 2011 05:00:00 +0100 5505890 http://www.medworm.com/index.php?rid=5505889&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161962%26dopt%3DAbstract Authors: Miller PW, Bender D Abstract Quick as a flash! (11) CS(2) can now be produced rapidly and with high radiochemical yields and specific radioactivities by the high temperature gas-phase reaction of (11) CH(3) I with the thionating agent P(2) S(5) . (11) CS(2) was found to be a highly reactive labelling reagent forming a range of [(11) C]dithiocarbamate compounds within extremely short reaction times. PMID: 22161962 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505889 Mon, 12 Dec 2011 05:00:00 +0100 5505889 http://www.medworm.com/index.php?rid=5505888&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161970%26dopt%3DAbstract Authors: Laville L, Charnay C, Lamaty F, Martinez J, Colacino E Abstract Underwater exploration: The ring-closing metathesis of N,N-diallyltosylamine (DATs) and diallyldiethyl malonate has been studied in aqueous micellar medium, at room temperature, in the presence of four different gemini cationic surfactants and various ruthenium catalysts. For the first time, the adsorption mechanisms and the reaction steps involved in this heterogeneous catalytic process were elucidated. PMID: 22161970 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505888 Mon, 12 Dec 2011 05:00:00 +0100 5505888 http://www.medworm.com/index.php?rid=5505887&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161973%26dopt%3DAbstract Authors: Tian H, Wang M, Zhao L, Guo YN, Guo Y, Tang J, Liu Z Abstract A magnetic personality: A unique dysprosium trigonal prism with a new polydentate Schiff-base ligand behaves as a single molecule magnet (SMM), which may stimulate further investigations into the relaxation dynamics of SMMs with different topologies. PMID: 22161973 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505887 Mon, 12 Dec 2011 05:00:00 +0100 5505887 http://www.medworm.com/index.php?rid=5505877&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162196%26dopt%3DAbstract Authors: Wu XF, Neumann H, Beller M Abstract Amides in mind! A novel palladium-catalyzed amino-carbonylation of in situ formed aryl nonaflates to give primary amides in moderate to excellent yields has been developed. PMID: 22162196 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505877 Mon, 12 Dec 2011 05:00:00 +0100 5505877 http://www.medworm.com/index.php?rid=5505874&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162238%26dopt%3DAbstract Authors: Ma Y, Liang J, Sun H, Wu L, Dang Y, Wu Y Abstract Here we report the rapid and convenient patterning of proteins on porous polymer film using the inverse microemulsion approach. Following this method, proteins, which were dissolved in water, were transferred into dichloromethane solution of polymers through the formation of inverse microemulsion by mixing the two solutions. The protein-containing microemulsion droplets accumulated automatically into large and stable ones on the surface of organic solution casting on solid substrates, and formed tightly packed microemulsion droplet arrays driven by surface tension. With the evaporation of organic solvent and water, the microemulsion droplet arrays, which act as the template, turn to honeycomb patterned pores bearing protein... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505874 Mon, 12 Dec 2011 05:00:00 +0100 5505874 http://www.medworm.com/index.php?rid=5505872&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162274%26dopt%3DAbstract Authors: Serhan Z, Borgogno A, Billault I, Ferrarini A, Lesot P Abstract The overall and detailed elucidation (including the stereochemical aspects) of enzymatic mechanisms requires the access to all reliable information related to the natural isotopic fractionation of both precursors and products. Natural abundance deuterium (NAD) 2D-NMR experiments in polypeptide liquid-crystalline solutions are a new, suitable tool for analyzing site-specific deuterium isotopic distribution profiles. Here this method is utilized for analyzing saturated C14 to C18 fatty acid methyl esters (FAMEs), which are challenging because of the crowding of signals in a narrow spectral region. Experiments in achiral and chiral oriented solutions were performed. The spectral analysis is supplemented by the th... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505872 Mon, 12 Dec 2011 05:00:00 +0100 5505872 http://www.medworm.com/index.php?rid=5505870&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162296%26dopt%3DAbstract Authors: Yin G, Wu T, Liu G Abstract Cheap and clean! A novel Pd-catalyzed oxidative intramolecular chloroamination of unactivated alkenes has been developed by using hydrogen peroxide as an oxidant and CaCl(2) as a chlorine source. A series of chlorinated piperidine derivatives has been obtained with high regio- and diastereoselectivities at room temperature. PMID: 22162296 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505870 Mon, 12 Dec 2011 05:00:00 +0100 5505870 http://www.medworm.com/index.php?rid=5505869&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162312%26dopt%3DAbstract Authors: Dou X, Han X, Lu Y Abstract It all adds up! A modified Feist-Bénary reaction employing a domino Michael-alkylation sequence was designed for the enantioselective synthesis of 3(2 H)-furanones. L-Threonine-derived tertiary amine/thiourea catalysts were prepared for the first time; such catalysts promoted the designed domino Michael-alkylation reactions in a highly enantioselective manner. PMID: 22162312 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505869 Mon, 12 Dec 2011 05:00:00 +0100 5505869 http://www.medworm.com/index.php?rid=5505868&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22162327%26dopt%3DAbstract Authors: Forgan RS, Wang C, Friedman DC, Spruell JM, Stern CL, Sarjeant AA, Cao D, Stoddart JF Abstract The self-assembly of three donor-acceptor ring-in-ring complexes, prepared from the π-electron-deficient tetracationic cyclophane, cyclobis(paraquat-4,4'-biphenylene), and three large π-electron-rich crown ethers (each 50-membered rings) containing dioxynaphthalene (DNP) and tetrathiafulvalene (TTF) units in pairs (DNP/DNP, DNP/TTF and TTF/TTF), is reported. (1) H NMR spectroscopic analyses are indicative of the formation of 1:1 complexes in CD(3) CN, whilst the charge-transfer interactions between the DNP and TTF units of the crown ethers and the tetracationic cyclophane have permitted the measurement of binding constants of up to 4×10(3)  M(-1) in CH(3) CN to be made usi... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505868 Mon, 12 Dec 2011 05:00:00 +0100 5505868 http://www.medworm.com/index.php?rid=5505896&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161809%26dopt%3DAbstract Authors: Buurmans IL, Ruiz-Martínez J, van Leeuwen SL, van der Beek D, Bergwerff JA, Knowles WV, Vogt ET, Weckhuysen BM Abstract A time-resolved in situ micro-spectroscopic approach has been used to investigate the Brønsted acidic properties of fluid-catalytic-cracking (FCC) catalysts at the single particle level by applying the acid-catalysed styrene oligomerisation probe reaction. The reactivity of individual FCC components (zeolite, clay, alumina and silica) was monitored by UV/Vis micro-spectroscopy and showed that only clay and zeolites (Y and ZSM-5) contain Brønsted acid sites that are strong enough to catalyse the conversion of 4-fluorostyrene into carbocationic species. By applying the same approach to complete FCC catalyst particles, it has been found that the fingerpri... Chemistry journals http://www.medworm.com/rss/comments.php?id=5505896 Fri, 09 Dec 2011 05:00:00 +0100 5505896 http://www.medworm.com/index.php?rid=5505893&cid=s_37952_59_f&fid=37952&url=http%3A%2F%2Fwww.ncbi.nlm.nih.gov%2Fentrez%2Fquery.fcgi%3Ftmpl%3DNoSidebarfile%26db%3DPubMed%26cmd%3DRetrieve%26list_uids%3D22161862%26dopt%3DAbstract Authors: Jin Z, Li YJ, Ma YQ, Qiu LL, Fang JX Abstract A cooperative couple: Cooperative bimetallic activation of CF and CO bonds gave rise to easy coupling with aryl fluorides and tosylates. Novel air- and moisture-stable diaminophosphine oxides derived from 1,1'-biphenyl-2,2'-diamine proved to be versatile preligands for the nickel-catalyzed cross-coupling of aryl Grignard reagents with a variety of deactivated aryl chlorides, fluorides, and tosylates. PMID: 22161862 [PubMed - as supplied by publisher] (Source: Chemistry) Chemistry journals http://www.medworm.com/rss/comments.php?id=5505893 Fri, 09 Dec 2011 05:00:00 +0100 5505893