Relaxation dynamics of stretched polymer chains traced by shear induced Shish‐Kebab structure

We have developed a morphologic method to investigate the relaxation processing of the stretched polymer chains in melts, in which an atomic force microscope probe was used to shear the surface of an isotactic polypropylene melt to obtain the isolated shish‐kebab structure. We present the results of the time dependence of length of the isolated shish‐kebab structure and the stress dependence of the kebab density along the direction of shish in this paper. Our results demonstrate that the shear‐oriented polymer melts show the relaxation dynamics of worm‐like chain where the length deficit of the isolated shish‐kebab structure is scaled with the relaxation time as a power of 1/3. The melting behavior of shish‐kebab structure was also investigated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 907–914     

Multireference calculations on low-lying states and the X~3 Π_u -~3 Π_g absorption spectra of indium dimers

Multireference configuration interaction calculations are carried out on 11 Λ-S low-lying electronic states of indium dimers. The states are investigated with spin-orbit pseudopotentials via the state-interacting method, and characterized by fitted spectroscopic constants based on computed potential energy curves. The vibrational structures of the double-potential well 0+g (I) ( 3 Σ g ) state are also analyzed. The experimentally observed absorption spectrum centred at ～ 13000cm-1 is simulated and assigned to X 3 Πu (v=0)-3Πg transition according to the present ab initio calculations on transition energies and dipole moment functions.     

High-performance Cu/ZnO/Al2O3 catalysts for methanol steam reforming with enhanced Cu-ZnO synergy effect via magnesium assisted strategy

Methanol steam reforming (MSR) is an attractive approach to produce hydrogen for fuel cells.Due to the limited catalyst loading volume and frequent start-ups an...     

Development of Sn2+-based oxyfluoride photocatalyst with visible light response of ca.650 nm via strengthened hybridization of Sn 5s and 02p orbitals

The hybridization between the outmost s orbitals of metal (Bi3+,Sn2+,Pb2+,Ag+) and O 2p orbitals has been widely employed to develop innovative semiconductors w...     

Facile synthesis of sulfenyl-substituted isocoumarins,heterocycle-fused pyrones and 3-(inden-1-ylidene)isobenzofuranones by FeCl3-promoted regioselective annulation of o-(1-alkynyl)benzoates and o-(1-alkynyl)heterocyclic carboxylates with disulfides

Reported herein is the FeCl₃-promoted intermolecular sulfoesterification of o-(1-alkynyl)benzoates with disulfides, which provides a convenient and efficient method for synthesis of 4-sulfenylisocoumarins. Various functional groups such as methoxy, halides, ester, cyano and silicon groups in the substrates are tolerated, and heterocycle-fused chalcogenylpyrones are also successfully achieved directly from the corresponding heterocyclic precursors under the same reaction conditions. In addition, starting from diynylbenzoate, this reaction sequence can be combined with a bicyclization step leading to the tetracyclic (E)-3-(2-phenyl-3-phenylchalcogenylinden-1-ylidene)isobenzofuranone frameworks with high regiospecificity and exclusive trans stereoselectivity.     

Immobilized palladium on surface-modified Fe3O4/SiO2 nanoparticles: as a magnetically separable and stable recyclable high-performance catalyst for Suzuki and Heck cross-coupling reactions

A palladium-based catalyst (Fe₃O₄/SiO₂/HPG–OPPh₂–PNP) supported on chlorodiphenylphosphine-functionalized magnetic nanoparticles was successfully prepared from Fe₃O₄/SiO₂ with sequential attachment of glycerol and chlorodiphenylphosphine, followed by treatment of an ethanolic solution of palladium chloride with hydrazine. The as-prepared catalyst was characterized by ICP-AES, FTIR, XRD, SEM, and TEM. The Fe₃O₄/SiO₂/HPG–OPPh₂–PNP was found as a magnetically separable and highly active catalyst for Suzuki coupling reactions of aryl iodides, bromides, and chlorides as well as Heck reactions of aryl iodides and bromides. Under appropriate conditions, all reactions afforded the desired products in moderate to excellent yields. Moreover, this catalyst can be easily recovered by using a magnetic field and directly reused for at least six cycles without significant loss of its activity.     

A new electronically deficient atropisomeric diphosphine ligand (S)-CF3O-BiPhep and its application in asymmetric hydrogenation

A new electronically deficient atropisomeric diphosphine ligand (S)-CF₃O-BiPhep was synthesized from 1-bromo-3-(trifluoromethoxy)benzene in high yield. The key steps included oxidative coupling with anhydrous ferric chloride and optical resolution by (+)-DMTA. The ligand afforded high performance for Ir-catalyzed asymmetric hydrogenation of quinolines with ee up to 92% and TON up to 25,000. It was also successfully applied to the Pd-catalyzed asymmetric hydrogenation of simple indoles with ee up to 87% and Rh-catalyzed asymmetric 1,4-addition of phenylboronic acid to 2-cyclohexenone with 97% ee.     

The effect of water molecule on the thermal stability of lanthanide compounds with 1,3-benzeneditetrazol-5-yl

Six lanthanide compounds [Ln(H₂O)₉](m-BDTH)₃·9(H₂O) where Ln = La (1), and [Ln(H₂O)₈](m-BDTH)₃·9(H₂O) (m-BDTH₂ = 1,3-benzeneditetrazol-5-yl) where Ln = Lu (2), Yb (3), Er (4), Ho (5) and Y (6) were hydrothermally synthesized and characterized by elemental analyses, infrared spectra, powder X-ray diffraction (PXRD) and X-ray single crystal diffraction. PXRD indicates that 2–6 are isomorphous. Structural analyses reveal that 1 is coordinated by nine water molecules forming a capped-square antiprism, while 2–6 are coordinated by eight water molecules forming a simple square antiprismatic geometry. Effects of water molecules on thermal stability were also discussed by thermogravimetric (TG), DSC, and PXRD under different temperatures. TG analyses suggest that 1 loses lattice and coordinated water molecules with no diacritical boundary, and 6 removes lattice water molecules first and then coordinated water molecules. DSC and PXRD further confirm the consequence.