Transesterification of Cyclic Carbonates to Dimethyl Carbonate Using Effective Oxide Catalyst at Ambient Conditions: Environmentally Warm-hearted Composite <<>>

Written by Meenakshisundaram Sankar, Srikanth Satav, Palanichamy Manikandan on March 31, 2010 – 12:11 pm -

Perpetual coalescence at ambient conditions: Dimethyl carbonate (DMC) is an important methylating and carbonylating power. Transesterification of cyclic carbonates using methanol for the fusing of DMC is environmentally congenial. CaO-ZnO catalysts, planned by a wet impregnation method, are moving catalysts for the transesterification of ethylene carbonate using methanol in quantity and in endless reactors. Yields of ca. 84 % DMC can be achieved at ambient conditions <<>>

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Catalytic Asymmetric 1,3-Dipolar Cycloaddition of [alpha]-Iminonitriles <<>>

Written by Rocío Robles-Machín, Inés Alonso, Javier Adrio, Juan C. Carretero on March 31, 2010 – 12:09 pm -

Improving the structural scope: A catalytic asymmetric 1,3-dipolar cycloaddition involving [alpha]-iminonitriles as azomethine precursors has been developed. In the imperturbability of AgOAc/Taniaphos as catalyst technique the counteraction of [alpha]-iminonitriles with dimethyl fumarate and N-methyl maleimide affords 2-cyanopyrrolidines with all right endo selectivity and enantioselectivity (68-[ge]99 % ee) <<>>

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A Scanning Probe Microscopy Studio of Annulated Redox-Active Molecules at a Liquid/Solid Interface: The Overruling of the Alkyl Gyve Paradigm <<>>

Written by Bo Liu, Ying-Fen Ran, Zhihai Li, Shi-Xia Liu, Chunyang Jia, Silvio Decurtins, Thomas Wandlowski on March 31, 2010 – 12:09 pm -

Overruled! The self-assembly of a novel arrange of fused donor-acceptor molecules (1) comprising hexaazatriphenylene and tetrathiafulvalene branches was studied by STM at the liquid/solid interface. A 2D assembled chiral penetrable network of C3 well-meaning was found, which is dictated by steady interactions of the extended [pi]-conjugated cores of the fused units with the HOPG substrate overruling the directional forces of alkyl chains <<>>

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Importantly Competent RhI-Catalyzed Asymmetric Hydrogenation of [beta]-Amino Acrylonitriles <<>>

Written by Miaofeng Ma, Guohua Hou, Tian Sun, Xiaowei Zhang, Wei Li, Junru Wang, Xumu Zhang on March 31, 2010 – 12:09 pm -

It takes two to TangPhos: [beta]-Amino acrylonitriles can be willingly processed from acetonitriles. Both of the E/Z isomers undergo hydrogenation with choice enantioselectivity by using the Rh-TangPhos (TangPhos=1,1[prime]-di-tert-butyl-(2,2[prime])-diphospholane) catalyst system. The products, chiral [beta]-amino nitriles, are valuable chiral edifice blocks for multifarious drugs <<>>

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Aryl Phosphoramides: Functional Electrophiles for Suzuki-Miyaura Coupling Catalyzed by a NiCl2/dppp Approach (dppp=1,3-Bis(diphenylphosphino)propane) <<>>

Written by Yu-Long Zhao, You Li, Yu Li, Lian-Xun Gao, Fu-She Han on March 31, 2010 – 12:09 pm -

Suzuki-Miyaura coupling: We spill the beans a new scenario for phenol activation in the basic Suzuki-Miyaura coupling of phenol derivatives activated by forming aryl bis(2-oxo-3-oxazolidinyl)phosphines as a highly economic and broadly right methodology for the mixed combining of biaryls and heterobiaryls (see scheme). The use of freely available, enduring NiCl2/dppp (dppp=1,3-bis(diphenylphosphino)propane) as the catalyst process also provides an smug go forward <<>>

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Soluble and Columnar Solvent Crystalline Peropyrenequinones by Coupling of Phenalenones in Caesium Hydroxide <<>>

Written by Noémie Buffet, Éric Grelet, Harald Bock on March 31, 2010 – 12:09 pm -

Shades of violet: The nitrogen-free homologues of perylene tetracarboxylic diimide dyes have been disposed. CsOH succeeds where KOH fails to team a few sterically nagging hydroxyphenalenones into the esterifiable precursors of [pi]-stacking long-wavelength absorbing disks (see figure) <<>>

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Metal-Organic Frameworks with Exceptionally Rich Methane Uptake: Where and How is Methane Stored? <<>>

Written by Hui Wu, Jason M. Simmons, Yun Liu, Craig M. Brown, Xi-Sen Wang, Shengqian Ma, Vanessa K. Peterson, Peter D. Southon, Cameron J. Kepert, Hong-Cai Zhou, Taner Yildirim, Wei Zhou on March 31, 2010 – 12:09 pm -

Metal-organic frameworks (MOFs) are a best-seller progenitors of physisorptive materials that have exhibited enormous take an oath for methane storage. So far, a inclusive sensitivity of their methane adsorption process is restful far between. Herein, we describe a full mechanistic study of methane storage in three milestone MOF compounds (HKUST-1, PCN-11, and PCN-14) the CH4 storage capacities of which are among the highest reported so far centre of all porous materials. The three MOFs consist of the verbatim at the same time dicopper paddlewheel less important construction units, but confine manifold natural linkers, foremost to cagelike pores with different sizes and geometries. From neutron authority diffraction experiments and careful information analysis, assisted by illustrious canonical Monte Carlo (GCMC) simulations and DFT calculations, we unambiguously revealed the painstaking locations of the stored methane molecules in these MOF materials. We rest that methane sensitivity takes appointment at the start at two types of rabid adsorption site: 1) the open Cu coordination sites, which show off enhanced Coulomb show toward methane, and 2) the van der Waals potential keep sites, in which the total dispersive interactions are enhanced due to the molecule being in connection with multiple "surfaces". Interestingly, the enhanced van der Waals sites are present exclusively in small cages and at the windows to these cages, whereas strapping cages with relatively without delay pore surfaces bind really sparse methane. Our results advance that further, reasoning expansion of new MOF compounds for methane storage applications should hub on enriching activate metal sites, increasing the book portion of obtainable tiny cages and channels, and minimizing the fraction of large pores <<>>

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Solution-Phase Racemization in the Deportment of an Enantiopure Solid Usher in <<>>

Written by Cristobal Viedma, Bastiaan J. V. Verkuijl, José E. Ortiz, Trinidad de Torres, Richard M. Kellogg, Donna G. Blackmond on March 31, 2010 – 12:09 pm -

Solution-phase racemization drives the progress of free chirality in the solid inject by the "chiral amnesia" treat first described by Viedma. The contemporary investigations lay the foundation for a happier understanding of the medium of the solid-phase deracemization by uncoupling the chemical have a claim to processes associated with the interconversion of enantiomers in the solution discontinue from the doc processes associated with solution-solid angle change via decay and reaccretion of molecules onto crystals. In addition, the enantiomer concentration profiles presented in this work, together with an analytical treatment of the racemization change in the bearing of redundancy enantiopure solid, unequivocally reconfirm the validity of the Meyerhoffer duplicated solubility guideline for systems below solution racemization conditions <<>>

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Molecular Organization of Amyloid Fibrils Formed by Residues 127 to 147 of the Altruist Prion Protein <<>>

Written by Ni-Shian Lin, John Ching-Hao Chao, Hsin-Mei Cheng, Fang-Chieh Chou, Chi-Fon Chang, Yun-Ru Chen, Yu-Jen Chang, Shing-Jong Huang, Jerry C. C. Chan on March 31, 2010 – 12:09 pm -

Amyloid fibrils are filamentous and insoluble forms of peptides or proteins. Proline has extensive been considered to be irreconcilable with the cross-[beta] structural device of amyloid fibrils. On the principle of solid-state NMR spectroscopy data, we tender a structural fabricate of an in-register similar [beta] contour sheet for the amyloid fibrils formed from a person prion protein fragment, huPrP127-47. We bear developed a homely solid-state NMR spectroscopy dexterousness to identify solvent-protected stability amide protons in a H/D the Bourse experiment without disaggregating the amyloid fibrils, from which we find out that proline residuum P137 does not disrupt the [beta]-sheet structure from G127 to G142. We suggest that the resultant curl at P137 generates a misconstrue between adjacent peptide strands to keep hydrogen bonding in the [beta]-sheet regions flanking the P137 surplus. Although proline can be okay integrated into the cross-[beta] design of amyloid fibrils, the kink formed at the position of the proline rest drive considerably enfeeble the hydrogen bonding internuncio the neighboring strands, unusually when the deviation locality is near the inner zone of a [beta] area <<>>

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Beige and Oxidized Triisopropylsilyl End-Capped Oligothienoacenes: A Combined Electrochemical, Spectroscopic, and Theoretical Office <<>>

Written by Juan Aragó, Pedro M. Viruela, Enrique Ortí, Reyes Malavé Osuna, Barbara Vercelli, Gianni Zotti, Víctor Hernández, Juan T. López Navarrete, John T. Henssler, Adam J. Matzger, Yoshitake Suzuki, Shigehiro Yamaguchi on March 31, 2010 – 12:09 pm -

This exploit presents an division of the structural, electrochemical, and optical properties of a pedigree of triisopropylsilyl end-capped oligothienoacenes (TIPS-Tn-TIPS, n=4-8) by combining cyclic voltammetry, spectroscopic techniques, and quantum-chemical calculations. TIPS-Tn-TIPS compounds species stable anarchist cations, and dications are simply obtained for the longest oligomers (n=7 and 8). Oxidation leads to the quinoidization of the conjugated backbone, from which electrons are above all extracted. The absorption and fluorescence spectra plain degree resolved vibronic structures even at lodge temperature, due to the unqualified molecular geometry. Two well-resolved vibronic progressions are observed at low temperatures due to the vibronic coupling, with run-of-the-mill modes showing wavenumbers of [ap]1525 and [ap]480 cm-1. Optical absorption bands disclose uncommon bathochromic dispersion with the oligomer length, indicative of the dimensions of [pi] conjugation. The optical properties of the oxidized compounds are characterized by in situ UV/Vis/NIR spectroelectrochemistry. The pink cation species certify two consuming absorption bands emerging at energies lower than in the uncommitted compounds. The generation of the dication is solely detected for the heptamer and the octamer, and shows a new troop at transitional energies. Optical details are interpreted with the succour of density functional theory calculations performed at the B3LYP/6-31G** level, both for the neutral and the oxidized compounds <<>>

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