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1.
Giovanna Marini-Bettòlo Soumya P. Sahoo Gerald A. Poulton Thomas Y.R. Tsai Karel Wiesner 《Tetrahedron》1980,36(6):719-721
Some years ago an empirical rule, which allows the prediction of product stereochemistry in cis-photocycloaddition reactions of α,β-unsaturated ketones and olefins was tentatively proposed. Several additional examples, both selected from the literature and synthesized in our laboratory, seem to strengthen the validity of the rule. 相似文献
2.
G. Sivalingam R. Karthik Giridhar Madras 《Journal of Analytical and Applied Pyrolysis》2003,70(2):631-647
The thermal degradation/modification dynamics of poly(-caprolactone) (PCL) was investigated in a thermogravimetric analyzer under non-isothermal and isothermal conditions. The time evolution of the molecular weight distribution during degradation was studied using gel permeation chromatography. Experimental molecular weight evolution and weight loss profile were modeled using continuous distribution kinetics. The degradation exhibited distinctly different behavior under non-isothermal and isothermal heating. Under non-isothermal heating, the mass of the polymer remained constant at initial stages with rapid degradation at longer times. The Friedman and Chang methods of analysis showed a 3-fold change (from 18 to 55–62 kcal mol−1) in the activation energy from low temperatures to high temperatures during degradation. This suggested the governing mechanism changes during degradation and was explained using two parallel mechanisms (random chain scission and specific chain end scission) without invoking the sequential reaction mechanisms. Under isothermal heating, the polymer degraded by pure unzipping of specific products from the chain end. 相似文献
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Cost effective and green protocols for the synthesis of two new series of coumarin based blue light emitting fluorophores named as ‘Beta Fluors’ and ‘Alpha Fluors’ are described. The coumarin alkylamide based Beta Fluors are developed using a one-step multi-component process in the presence of phenyl boronic acid as an efficient green catalyst. The Alpha Fluors are structured with coumarin–triazole–carboxamide peptidomimetics and their synthesis involves the ‘click with MCR’ concept. The new fluorophores gave high Stoke’s shift values for the emission wavelengths and their structural features are promising for further fine tuning to obtain preferred emission maxima. 相似文献
5.
Soumya Chakrabarti 《General Relativity and Gravitation》2017,49(2):24
An analogue of the Oppenheimer–Synder collapsing model is treated analytically, where the matter source is a scalar field with an exponential potential. An exact solution is derived followed by matching to a suitable exterior geometry, and an analysis of the visibility of the singularity. In some situations, the collapse indeed leads to a finite time curvature singularity, which is always hidden from the exterior by an apparent horizon. 相似文献
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Lakshmanan Sivalingam Govindaraj Dharman Mahalakshmi K. Thirumurugan K. Ramalakshmi N. Antony S. Arul 《Structural chemistry》2021,32(4):1597-1609
Structural Chemistry - Chalcone derivatives (7a–k) have been synthesized and characterized by 1H-NMR, 13C-NMR, mass, and elemental analysis. The synthesized compounds 7a, 7d, and 7g have been... 相似文献
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In this article, we propose a stochastic search based method, namely genetic algorithm in conjunction with density functional theory to evaluate structures of water‐halide microclusters, with the halide ion being Cl?, Br?, and I?. Once the structures are established, we evaluate the infrared spectroscopic modes, vertical detachment energies and natural population analysis based charges. We compare our results with available experimental and theoretical results. © 2012 Wiley Periodicals, Inc. 相似文献
10.
Single crystals of a new calcium(II) complex of benzilic acid, [Ca(C14H11O3)2(C14H12O3)2] have been successfully grown by gel diffusion technique at room temperature. Single crystal X-ray diffraction study reveals that the compound belongs to orthorhombic system with space group Fddd. The adjacent CaO8 units are linked via O–H–O interaction to form one dimensional polymeric chains. The extensive hydrogen bonding interactions lead to a supramolecular structure. The grown crystals were further characterized by elemental analysis, FT-IR, UV–Visible, thermogravimetric, powder X-ray diffraction and solid state photoluminescence studies. 相似文献