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991.
Watson William H. Bodige Satish G. Marchand Alan P. Chong Hyun-Soon 《Structural chemistry》2000,11(4):257-260
Acid-catalyzed reaction of pentacyclo[5.4.0.02,6.03,10.05.9]undecane-8,11-dione (1) with penta(ethylene glycol) produced two cage-functionalized, ketal-containing crown ethers, i.e., 2 and 3, in low yield. The structure of 2 was established unequivocally by direct methods. Alkali metal picrate extraction data obtained for 2 and for a structurally related model compound, i.e., 18-crown-6,indicate that 2 is an inefficient alkali metal picrate extracting agent. 相似文献
992.
D. K. Mohapatra P. L. Nayak S. Lenka 《Journal of polymer science. Part A, Polymer chemistry》1997,35(15):3117-3124
Substituted aromatic compounds incorporated–cardanol–formaldehyde novolac resins were synthesized by acid base catalyzed reactions. A number of improved high temperature stable interpenetrating polymer networks (semi-IPNs) were prepared by condensing novolac resins and polyurethanes prepared from castor oil and diisocyanates of varying NCO/OH ratio. The structure of these semi-IPNs were studied using various characterization techniques such as IR, nuclear magnetic resonance (NMR) spectra. The scanning electron microscopy of some of the semi-IPNs have been studied and the morphology has been examined. The samples were subjected to wide angle X-ray diffraction analysis. The degree of crystallinity (Xcr) was computed on the basis of the crystal defect concept, developed by Ruland and Vonk. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3117–3124, 1997 相似文献
993.
In the present paper the theory of micropolar generalized thermoelastic continua has been employed to study the propagation
of plane waves in micropolar thermoelastic plates bordered with inviscid liquid layers (or half-spaces) with varying temperature
on both sides. The secular equations in closed form and isolated mathematical conditions are derived and discussed. Thin plate
and short wave length results have also been deduced under different cases and situations and discussed as special cases of
this work. The results in case of conventional coupled and uncoupled theories of thermoelasticity can be obtained both in
case of micropolar elastic and elastokinetics from the present analysis by appropriate choice of relevant parameters. The
various secular equations and relevant relations have been solved numerically by using functional iteration method in order
to illustrate the analytical developments. Effect of characteristic length and coupling factors have also been studied on
phase velocity. The computer simulated results in case of phase velocity, attenuation coefficient and specific loss of symmetric
and skew symmetric are presented graphically. 相似文献
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998.
Chuan‐Zhi Liu Satish Koppireddi Hui Wang Dan‐Wei Zhang Zhan‐Ting Li 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):232-236
Halogen bonding has been used to glue together hydrogen‐bonded short arylamide foldamers to achieve new supramolecular double and quadruple helices in the solid state. Three compounds, which bear a pyridine at one end and either a CF2I or fluorinated iodobenzene group at the other end, engage in head‐to‐tail N???I halogen bonds to form one‐component supramolecular P and M helices, which stack to afford supramolecular double‐stranded helices. One of the double helices can dimerize to form a G‐quadruplex‐like supramolecular quadruple helix. Another symmetric compound, which bears a pyridine at each end, binds to ICF2CF2I through N???I halogen bonds to form two‐component supramolecular P and M helices, with one turn consisting of four (2+2) molecules. Half of the pyridine‐bearing molecules in two P helices and two M helices stack alternatingly to form another supramolecular quadruple helix. Another half of the pyridine‐bearing molecules in such quadruple helices stack alternatingly with counterparts from neighboring quadruple helices, leading to unique quadruple helical arrays in two‐dimensional space. 相似文献
999.
Nilofar Baral Seetaram Mohapatra Bishnu Prasad Raiguru Nilima Priyadarsini Mishra Pravati Panda Sabita Nayak Satyendra Kumar Pandey P. Sudhir Kumar Chita Ranjan Sahoo 《Journal of heterocyclic chemistry》2019,56(2):552-565
A new series of novel chromene‐based oxadiazole derivatives were synthesized from a variety of chromene‐based amidoximes with readily available carboxylic acids under conventional oil bath heating as well as under microwave irradiation. The use of commercially available EDCI and HOBt as coupling reagents in DMF combined with microwave heating resulted in high yields and purities of the product 1,2,4‐oxadiazoles in an expeditious manner. This methodology is successfully applied to synthesize 18 numbers of new 2H‐chromene‐substituted 1,2,4‐oxadiazole derivatives in good to high yields. The structure of the product was ascertained by X‐ray crystallographic analysis. All the synthesized compounds were evaluated for their in vitro antibacterial activity against two different pathogenic bacterial strains, that is, Escherichia coli (MTCC614) and Klebsiella pneumoniae (MTCC4031). The obtained results from in vitro antimicrobial assays indicated that 6g and 6h exhibited good antibacterial activity nearer to the standard drug, gentamicin. The molecular docking studies showed that compounds 6g and 6h show hydrogen bonding interaction with the bacterial target DNA gyrase of E. coli. 相似文献
1000.
Susanta K. Nayak Giancarlo Terraneo Quirino Piacevoli Federica Bertolotti Patrick Scilabra John T. Brown Sergiy V. Rosokha Giuseppe Resnati 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(36):12586-12589
Although instrumental for optimizing their pharmacological activity, a molecular understanding of the preferential interactions given by volatile anesthetics is quite poor. This paper confirms the ability of halothane to work as a hydrogen‐bond (HB) donor and gives the first experimental proof that halothane also works as a halogen‐bond (HaB) donor in the solid state and in solution. A halothane/hexamethylphosphortriamide co‐crystal is described and its single‐crystal X‐ray structure shows short HaBs between bromine, or chlorine, and the phosphoryl oxygen. New UV/Vis absorption bands appear upon addition of diazabicyclooctane and tetra(n‐butyl)ammonium iodide to halothane solutions, indicating that nitrogen atoms and anions may mediate the HaB‐driven binding processes involving halothane as well. The ability of halothane to work as a bidentate/tridentate tecton by acting as a HaB and HB donor gives an atomic rationale for the eudismic ratio shown by this agent. 相似文献