共查询到20条相似文献,搜索用时 156 毫秒
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5-芳基-2-呋喃甲酸及其衍生物具有调节植物生长等作用[4].我们通过大量的实验,选用PTC法,利用5-芳基-2-呋喃甲酰氯与芳胺和芳氧基乙酰肼反应,合成了新化合物Ⅱ和Ⅳ:RCOClO(Ⅰ)ArNH2/PEG-400→RCONHAr(Ⅱ)ONaOH/... 相似文献
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通过Fe3(CO)(12)、硫醇(硫酚)和EtMgBr所形成的络盐[(μ-CO)(μ-RS)Fe2(CO)6]-Mg+Br与氯代芳酰氯的原位反应,合成了通式为(μ-RS)(μ-o-ClC6H4CO)Fe2(CO)6和(μ-RS)(μ-m-ClC6H4CO)Fe2(CO)6(R=n-Ru,t-Bu,Ph)的6个新桥芳酰基铁硫配合物,并用C/H分析、IR和1HNMR表征了它们的结构。 相似文献
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通过Fe3(CO)12、硫醇(硫酚)和EtMgBr所形成的络盐[(μ-CO)(μ-RS)Fe2(CO6)》-Mg^+Br与氯代芳酰氯的原位反应,合成了通式为(μ-RS)(μ-o-ClC6H4CO)Fe2(CO6)和(μ-RS)(μ-m-ClC6H4CO)Fe2(CO)6(R=n-Bu,t-Bu,Ph)的6个新桥芳酰基铁硫配合物,并用C/H分析、IR和^1HNMR表征了它们的结构。 相似文献
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配体结构对三元混配配合物分子内芳环堆积作用的影响 总被引:5,自引:1,他引:5
用pH电位滴定法测定了含1,10-邻菲咯啉(Phen)和羧酸(CA)配体的三元混配配合物Pd(Phen)(CA)+体系的稳定常数,比较和讨论了各种三元混配物之间的稳定性差异。实验结果表明:在三元混配物Pd(Phen)(PCA)+中(PCA,苯基羧酸)存在分子内芳环堆积作用,堆积程度依赖于苯基和配位的羧酸根之间的亚甲基数目,最适宜堆积的苯基羧酸是2-苯乙酸和3-苯丙酸。 相似文献
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担载Fe2(CO)9络合物及其分散型Fe催化剂的CO吸脱附和催化作用 总被引:1,自引:0,他引:1
担载于Al2O3和ZrO2上的Fe(CO)9络合物的羰基在真空中极易脱附,在Ar或H2中250℃左右也可完全脱羰而成分散型催化剂。以ZrO2为载体者在Ar中低温下易发生表面岐化反应而生成CO2,高温下生成少量CH4。吸附于分散型催化剂上的CO在Ar或H2中均易发生岐化反应,以ZrO2为载体者在H2中发生加氢反应而生成CH4,在CO加氢中其反应物除了大量CO2外还有少量CH物。原位FT-IR谱表明以 相似文献
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本文研究了3种1-(芳酰基)-4[4'-(2,2,6,6-四甲基哌啶)-1-氧自由基]氨基硫脲化合物(ATSCPO)分别同通用阻聚剂(CIH),如对苯二酚(HQ),苯醌(BQ),吩噻嗪(PT)及二乙羟胺(DEHA)组成的混合阻聚剂对AIBN引发的MMA自由基聚合的影响,研究结果表明:当[ATSCPP]/CIH=5:1时,除ATSCPO-BQ外,其余阻聚效果均较ATSCPO和CIH单独用作阻聚剂时高 相似文献
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The elastin-derived polypentapeptide, poly(VPGVG), and analogs are becoming model systems for protein as well as forming a new class of biomaterials. The β-spiral of poly(VPGVG) represents a new family of molecular structures in fibrous proteins. In particular for our interests here, aromatic amino acid residue substitutions at position four of poly(VPGVG) give rise to new polypeptides with interesting properties of increased elastic modulus, pressure sensitivity, etc. Molecular mechanics computations were carried out to answer the question, can the polypeptides with Phe, Tyr, and Trp substitution at position four of poly(VPGVG) form a β-spiral structure like poly(VPGVG)? Employed in this study was a combination of conformational search using ECEPP/2 and the build-up strategy and of molecular dynamics calculations using CHARMm. The results indicate that the VPGX Type II β-turn structure appears to be the most prominent secondary structural feature for the three aromatic residues containing polypentapeptides, although there is more evidence for VPGFG and VPGVG to assume the VPGVG-type structure than for VPGWG to do so. The study also shows that the aromatic side chains do not interrupt the β-spiral structure, even in the case of tryptophan. 相似文献
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《Computational and Theoretical Polymer Science》2000,10(1-2):177-187
Three representative members of the family of poly(α-alkyl β-l-aspartate)s (PAALA-12, -16 and -18) have been investigated using Monte Carlo simulation of an atomistically explicit model. At the temperatures investigated, the main chains (helices) are arranged in highly regular layers, while the space between layers is filled by the alkyl side chains. The molecular structure of the inter-layer region is found to be very approximately liquid-like. The simulations are also able to predict the anomalous (densification) behavior of the PAALAs as the temperature is raised through the transition value. 相似文献
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Tian‐Jun Yue Ming‐Chao Zhang Ge‐Ge Gu Li‐Yang Wang Wei‐Min Ren Xiao‐Bing Lu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(2):628-633
The precise synthesis of poly(thioester)s with diverse structures is still a significant challenge in the polymeric materials field. Herein, we report a novel approach to the synthesis of well‐defined poly(thioester)s by the controlled alternating copolymerization of cyclic thioanhydrides and episulfides induced by simple organic ammonium salts. Both the cation and anion have strong effects on the copolymerization. [PPN]OAc ([PPN]=bis(triphenylphosphine)iminium) with a bulky cation was proven to be efficient in initiating this polymerization, yielding poly(thioester)s with a completely alternating structure, controlled molecular weight, and narrow polydispersity. The poly(thioester) obtained from succinic thioanhydride and propylene sulfide is a typical semicrystalline material, possessing a high refractive index of up to 1.78. Because it uses readily available monomers, this method is expected to open up a new route to poly(thioester)s with diverse structures and properties. 相似文献
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David Djurado Maciej Sniechowski Marc Bée Mark Johnson Miguel A. Gonzalez Patrice Rannou Adam Pron 《Macromolecular Symposia》2006,241(1):28-33
Numerical methods of molecular dynamics have been combined to measurements of X-ray and neutron scattering in order to obtain a realistic view of structural and dynamical disorder properties of conducting compounds of so called “plastdoped” poly(aniline)s. This combination allowed us to propose for the whole family of these compounds one generic model of a layered structure in which exist statistical fluctuations of the electronic density along the stacking direction of alternating molecular layers. The most part of the dynamics in the 10−13–10−9 s time range concerns the motions of protons borne by the flexible tails of doping counter-ions contained in the structure. We found that the molecular dynamics is characterized by both broad time and spatial distributions. These experimental facts coupled to those obtained with electrical conductivity measurements indicate that the high mobility of the counter-ion sublattice seems to be a prerequisite to promote a global metal like electronic behaviour of the polymer films. 相似文献
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《高分子科学杂志,A辑:纯化学与应用化学》2013,50(3):145-175
Novel hybrid organic–inorganic network materials have been generated based on poly(propylene oxide) (PPO) and tetramethoxysilane (TMOS). The PPO source chosen for this study was the family of JEFFAMINE®s often employed as epoxy curing agents. These materials were end–functionalized with trialkoxysilane groups which later were exploited in the sol–gel reaction. The sol–gel variables of water and acid catalyst concentration had little influence on the final structure and properties of the resulting network materials for the ranges probed. Increasing the TMOS content, however, generated a structure that angle X-ray scattering revealed a correlation length associated with a silicate phase separated by PPO chains, which increased with PPO molecular weight, as expected. 相似文献
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聚芳醚酮树脂的分子设计与合成及性能 总被引:1,自引:0,他引:1
聚芳醚酮树脂是20世纪发展起来的重要特种工程塑料.因其优良的耐热、耐腐蚀、耐摩擦及生物相容性好等特点,在国防军工、武器装备、航空航天、电子、汽车、机械、石油工业、核能及理疗卫生等高技术领有广泛的应用.此类材料大都采用双酚单体和双氟单体通过A2+B2型亲核缩聚反应制备.这类聚合物的分子结构对材料的性能影响较大,一般情况下分子链由醚、酮、苯三元规整结构构成时,聚合物为半结晶态;然而,当分子结构中存在侧基或其他非规整结构往往破坏聚合物的结晶结构,聚合物呈现无定型态.半结晶聚芳醚酮聚合物具有非常优异的耐热、耐化学稳定性一般作为结构型材料使用;无定型聚芳醚酮具有良好的加工性能,并且可进行一些功能化成为一类优异的功能型材料.本文从结构与性能关系出发,介绍了聚芳醚酮树脂种类,聚芳醚酮树脂的发展历程及合成方法;探讨了聚芳醚酮材料结构与性能关系;总结了功能性聚芳醚酮材料的前沿进展;最后结合实际展望了聚芳醚酮的应用发展方向. 相似文献
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Alvarez C Lozano AE de Abajo J de la Campa JG Capitán MJ Ezquerra TA 《The Journal of chemical physics》2004,120(18):8815-8823
The effect of molecular structure on the gamma relaxation dynamics has been studied in a set of aromatic poly(isophthalamide)s. This polymer family differ in the bridge group between phenylene rings [hexafluoroisopropylidene (C(CF(3))(2)) or ether] and also in the presence of t-butyl groups (C(CH(3))(3)) as pendant substituent on the five position of isophthalic ring. The results obtained from wide angle x-ray scattering in the glassy state indicated that both (C(CF(3))(2)) and (C(CH(3))(3)) groups favor the separation between chains, which is reflected on different interchain average distances. Dielectric experiments showed that both bulky groups favor the mobility in the glassy state. Molecular modelling methods were used to know the kind of molecular motions associated to the dielectric relaxation observed below the glass transition temperature. 相似文献