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排序方式: 共有254条查询结果,搜索用时 78 毫秒
61.
S. Meenakshi V. Vijayakumar S.N. Achary 《Journal of Physics and Chemistry of Solids》2011,72(6):609-612
The results of high-pressure angle dispersive X-ray diffraction measurements up to 34.3 GPa on the double perovskite Ba2MgWO6 are presented. The ambient rock salt phase (SG: Fm-3m) is found to be stable up to the highest pressure of the present measurements. The third order Birch-Murnaghan equation of state when fitted to pressure-volume data, yielded a zero pressure bulk modulus (B0),and its first and second pressure derivatives as 137.0(81) GPa, and 3.9(5) and −0.03 GPa−1, respectively. 相似文献
62.
Chinnaswamy Thangavel Vijayakumar Palanichamy Sivasamy 《European Polymer Journal》2007,43(7):3028-3035
Polyesterification of adipic acid and maleic anhydride with 1,3-bis(2-hydroxyethoxy)benzene (HER) in the presence of toluene-4-sulphonic acid was carried out using melt condensation technique. The structural characterization of the synthesized polyesters had been carried out using Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectroscopic methods. The thermal properties of the polyesters were studied using differential thermal analysis (DTA) and thermogravimetric analysis (TGA). The activation energies for the thermal degradation of the polyesters were calculated by the method of Dharwadkar and Kharkhanavala and discussed. The char residue value at 600 °C indicated maleic anhydride based polyester is thermally more stable compared to the adipic acid based polyester. The mechanism of degradation of these polyesters is discussed. 相似文献
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Structural Chemistry - G-protein–coupled receptors are integral membrane proteins involved in signal transduction pathways, making them an appealing drug targets for a wide spectrum of... 相似文献
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Tanwistha Ghosh Shinji Nagasawa Neethi Raveendran Vibhu Darshan Akinori Saeki Vijayakumar C. Nair 《化学:亚洲杂志》2019,14(7):963-967
Precise control over the supramolecular organization of organic semiconducting materials guiding to exclusive face‐on or edge‐on orientation is a challenging task. In the present work, we study the preferential packing of thiophene oligomers induced through rational molecular designing and self‐assembly. The acceptor–donor–acceptor‐type oligomers having 2‐(1,1‐dicyano‐methylene)rhodanine as acceptor ( OT1 ) favored a face‐on packing, whereas that of functionalized with N‐octyl rhodanine ( OT2 ) preferred an edge‐on packing as evident from 2D‐grazing incidence angle X‐ray diffraction, tapping‐mode atomic force microscopy (AFM) and Raman spectroscopy analyses. The oligomers exhibited anisotropic conductivity in the self‐assembled state as an outcome of the preferred orientation, revealed by the conducting AFM experiment. 相似文献
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Praveen VK George SJ Varghese R Vijayakumar C Ajayaghosh A 《Journal of the American Chemical Society》2006,128(23):7542-7550
Self-assembled nanotapes of a few tailor-made oligo(p-phenylenevinylene)s (OPVs) have been prepared and used as supramolecular donor scaffold to study the fluorescence resonance energy transfer (FRET) to a suitable acceptor. In nonpolar solvents, FRET occurs with nearly 63-81% efficiency, exclusively from the self-assembled OPVs to entrapped Rhodamine B, resulting in the quenching of the donor emission with concomitant formation of the acceptor emission at 625 nm. The efficiency of FRET is considerably influenced by the ability of the OPVs to form the self-assembled aggregates and hence could be controlled by structural variation of the molecules, and polarity of the solvent. Most importantly, FRET could be controlled by temperature as a result of the thermally reversible self-assembly process. The FRET efficiency was significantly enhanced (ca. 90%) in a xerogel film of the OPV1 which is dispersed with relatively less amount of the acceptor (33 mol %), when compared to that of the aggregates in dodecane gel. FRET is not efficient in polar solvents due to weak self-organization of the chromophores. These results indicate that energy transfer occurs exclusively from the self-assembled donor and not directly from the individual donor molecules. The present study illustrates that the self-assembly of chromophores facilitates temperature and solvent controlled FRET within pi-conjugated nanostructures. 相似文献