重氮树脂-聚(4-羧酸苯基)乙炔自组装膜与光电转换

近年来 ,自组装及其形成的多层复合膜已经在导电、生物传感器及非线性光学等领域得到深入研究 ,特别是以聚阴离子与聚阳离子相互作用的静电自组装研究更为深入 .这一技术制备方法简单 ,无需特别的设备 ,对膜层厚度能随意调控 ,并以水作为介质 ,对环境无害 [1～ 3] .共轭高分子 (如聚苯胺、聚吡咯及聚苯亚乙烯等 )通过自组装形成共轭高分子膜 ,对制备具有导电、光电和传输等功能的薄膜半导体器件具有重要意义 .聚乙炔类是最早被发现且理论与应用研究最多的一类共轭高分子材料[4 ,5] .本文以聚 ( 4 -羧酸苯基 )乙炔 ( PCPA)为聚阴离子 ,以重…     

Analysis of cement and cement raw meal by atomic absorption spectrophotometry using a new fusion agent

A new fusion agent is proposed for the analysis of cement and cement raw meal using AAS. In the described method, 0.8 g of the fusion agent, consisting of equal portions of oxalic acid, lithium carbonate and lithium tetraborate, was mixed with 0.2 g of the sample, and the mixture was fused for 10 min at 925 degrees C in a platinum crucilbe. The fusion cake was dissolved with dilute hydrochloric acid (1 + 10) and diluted to 500 ml for the determination of Si, Al, Fe, Ti, Na and K expressed as SiO(2), Al(2)O(3), Fe(2)O(3), TiO(2), Na(2)O, and K(2)O respectively. For the determination of Ca and Mg (expressed as CaO and MgO respectively), 10 ml of the previous sample solution were mixed with 4 ml of 6% (m/v) lanthanum nitrate solution and the solution was diluted to 100 ml. The method was found to have good accuracy and precision. The time required to determine the eight elements was around 80 min for each sample.     

Design considerations and computer modeling related to the development of molecular scaffolds and peptide mimetics for combinatorial chemistry

Summary A critical issue in drug discovery utilizing combinatorial chemistry as part of the discovery process is the choice of scaffolds to be used for a proper presentation, in a three-dimensional space, of the critical elements of structure necessary for molecular recognition (binding) and information transfer (agonist/ antagonist). In the case of polypeptide ligands, considerations related to the properties of various backbone structures (-helix, -sheets, etc.; , space) and those related to three-dimensional presentation of side-chain moieties (topography; (chi) space) must be addressed, although they often present quite different elements in the molecular recognition puzzle. We have addressed aspects of this problem by examining the three-dimensional structures of chemically different scaffolds at various distances from the scaffold to evaluate their putative diversity. We find that chemically diverse scaffolds can readily become topographically similar. We suggest a topographical approach involving design in chi space to deal with these problems.     

β-lithiations of carboxamides. Synthesis of β-substituted-α,β-unsaturated amides

N-Methyl-2-methyl-3-(benzotriazol-l-yl)propanamide, on treatment with butyllithium forms a dianion which on treatment with alkyl and benzyl halides, aldehydes and ketones affords monosubstituted products; with ethyl p-toluate, a lactam is formed. The alkylated derivatives eliminate benzotriazole in the presence of base to afford trisubstituted α,β-unsaturated amides.