超价化合物的定义和成键特征初探

介绍一些描述超价化合物结构的理论,从改进的8电子规则和分子轨道理论出发,结合计算,对超价化合物结构进行解释.说明了超价化合物结构大量存在非键轨道的特征,同时给出了一个判断超价化合物的方法.     

现代高科技的基础材料──非整比化合物

本文从非整比化合物概念的形成历史,非整比化合物的结构形成机理以及非整比化合物的类型等几个方面,介绍了非整比化合物结构与性能的关系,并指出了非整比化合物在材料科学中的应用。     

杂多化合物催化性能的研究—酸碱对12-钨磷酸(盐)在苄醇氧化反应中的催化活性的影响

1.前言 在所有众多结构的杂多化合物中,至今为止,具有Keggin结构的杂多酸(盐)是研究得最充分、也是唯一商品化了的杂多化合物。近年来,有许多关于Keggin结构杂多化合物作为催化剂的研究结果和应用报道。这些催化反应许多是在液相中进行的。由于杂多化合物易受酸碱影响而使结构改变或破坏,因此,反应体系中的酸碱度对杂多化合物结构的稳定性和催化活性都有明显作用。所以,研究酸碱对杂多化合物结构和催化性能的影响具有重要意义。本文考察了12-钨磷酸(盐)在苄醇氧化反应中的催化活性以及酸碱对催化活性的影响。     

桥环化合物环数的计算与命名

近年来, 有关桥环化合物及具有笼形结构的脂环化合物的报道很多, 合成了多种新型结构的化合物, 给化学教学增添了新内容, 引起了学生的很大兴趣。     

含Sn一N键的混合三烃基锡氮杂环化合物的研究

报道了１５个含Ｓｎ一Ｎ键的混合三烃基锡氮杂环衍生物的合成及结构表征。随含氮杂环的不同，化合物分别是五配位的聚合结构和四配位的单体结构。对化合物的质谱作了较为详细的讨论。测定了化合物的生物活性，并对生物活性与结构的关系进行了讨论。     

水溶性有机材料的合成与结构的研究

本文采用新的合成方法,合成了双链磺酸盐、多羟基化合物和杂环的磺酸化合物,鉴定其结构,研究了结构与结构与性能的关系,并作为光亮镍的添加剂,获得实际应用。     

含均三嗪结构甲氧基丙烯酸酯化合物的合成及抑菌活性研究

采用亲核取代和消除反应,合成了7个含均三嗪结构的新型甲氧基丙烯酸酯化合物,目标化合物的结构经IR、1H NMR、HRMS进行表征。对目标化合物进行了真菌抑制活性实验,结果表明在50ug·m L-1浓度下,4个目标化合物表现出一定的真菌抑制活性。     

虚拟活性化合物的自动生成

虚拟活性化合物的自动生成是从药效团和预先设定的结构碎片出发,通过碎片选择、碎片组装和柔性构象搜索来获得虚拟活性结构。经过对HIV-1蛋白酶抑制剂药效团进行虚拟活性化合物生成,得到了16个虚拟活性化合物,通过构象分析发现生成的化合物满足药效团的限制条件。说明这一方法能够有效的生成虚拟活性结构,与药效团检索结果对比发现生成的虚拟活性结构新颖易于合成。     

原子簇化合物的结构规则

近年来,国外关于原子簇化合物的研究,诸如合成、性能、结构与结构规律的探讨等极为活跃。我国科学工作者在这方面也做了不少的研究工作。这里仅对结构规则的探讨,作些介绍。其中包括两个方面,一是硼烷和碳硼烷的结构规则,二是金属原子簇化合物的结构规则。一、硼烷和碳硼烷硼烷就是硼氢化合物。五十年代由于高能燃料的研究,合成了许多硼氢化合物,在研究它的性能的同时,对它的结构也进行了测定和     

霍尔电导检测器的选择性及响应因子

本文研究了反应炉温度对霍尔电导检测器的选择性的影响和霍尔电导检测器对不同结构的含卤素化合物的响应因子。结果表明,在其它含氮化合物的存在下,霍尔电导检测器可以有选择地检测低脂肪胺,对不同结构的氯代化合物的响应与化合物的结构无关,而只与其中氯原子的含量有关。     

邻苯二甲酰二肽的光诱导单电子转移环化反应合成哌嗪酮类化合物

邻苯二甲酰化的二肽(1)在光照下,经过单电子转移形成分子内双自由基(5),自由基(5)分子内耦合成环得到含哌嗪酮的化合物.此反应产率较好,可以成为合成哌嗪酮类化合物的新方法.所有新化合物均经NMR和MS确定其结构.     

Synthesis and characterization of novel dipeptide ester prodrugs of acyclovir

Four dipeptide (Gly-Gly, Gly-Val, Val-Val, Val-Gly) ester prodrugs of 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir, ACV) were synthesized. LC/MS was used to characterize the new prodrugs. Both 1H NMR and 13C NMR spectra of the four prodrugs of ACV were measured and assigned based on spectral comparison with compounds of similar structures.     

The effect of a sulphur bridge on the photochromic properties of indeno-fused naphthopyrans

The synthesis of four new 2,2-diphenyl-2H-naphtho[1,2-b]pyrans with a fused indeno group at the f face and a sulphur junction between the 2,2-phenyl groups is described. The photochromic properties in solution of these novel compounds were investigated under continuous irradiation. Compared to known indeno-fused naphthopyrans, these new compounds showed a significant bathochromic shift in the spectra of the open forms, faster ring closure kinetics and an expected decrease in the colourabilities.     

取代嘧啶化合物的合成和生物活性研究

合成了14个新型取代嘧啶类化合物,结构经质谱、红外光谱、氢核磁共振光谱和元素分析确证.杀虫、杀菌和除草活性测定结果表明,部分化合物具有良好的杀菌活性.在嘧啶环的2-位上导入二甲氨基时表现出杀菌活性,但在嘧啶环的5-位上有甲基取代基时,杀菌活性下降.在嘧啶的4-位导入苯氧基时,显示出良好的杀菌活性,如化合物3b,3c和3e,苯环上的最优取代基是2-硝基-4-三氟甲基.     

一种合成6或7位乙酰基Lumazine环系衍生物的新途径

标题化合物的合成目的,在于研究其结构与稳定性的关系,用其解释V_b2的生命前合成中某些反应的机理,有关此种化合物的合成文献报道甚少,而且步骤较多。     

β-Lactam Derivatives as Enzyme Inhibitors: Peptidic Derivatives of (<Emphasis Type="Italic">RS</Emphasis>)-2-Oxo-4-phenylazetidine-1-alkanoic Acids

Summary. 4-Phenylazetidine-2-one was transformed into 4-phenylazetidine-1-alkanoic acids, which were reacted in the presence of diphenylphosphoroazidate with amino acid esters and dipeptide esters yielding β-lactam peptides with different spacers between the lactam ring and the peptide moiety. All structures were established by elementary analyses, HPLC, optical rotation, and spectroscopic data and all new compounds were tested as inhibitors of PPE using standard procedures. Four compounds exhibited a weak activity compared with the standard inhibitor trifluoroacetyl-l-val-l-tyr-l-val.     

β-Lactam Derivatives as Enzyme Inhibitors: Peptidic Derivatives of ( RS )-2-Oxo-4-phenylazetidine-1-alkanoic Acids

4-Phenylazetidine-2-one was transformed into 4-phenylazetidine-1-alkanoic acids, which were reacted in the presence of diphenylphosphoroazidate with amino acid esters and dipeptide esters yielding β-lactam peptides with different spacers between the lactam ring and the peptide moiety. All structures were established by elementary analyses, HPLC, optical rotation, and spectroscopic data and all new compounds were tested as inhibitors of PPE using standard procedures. Four compounds exhibited a weak activity compared with the standard inhibitor trifluoroacetyl-l-val-l-tyr-l-val.     

Photoelectron spectra and structures of three cyclic dipeptides: PhePhe, TyrPro, and HisGly

We have investigated the electronic structure of three cyclic dipeptides: cyclo(Histidyl-Glycyl) (cHisGly), cyclo(Tyrosyl-Prolyl) (cTyrPro), and cyclo(Phenylalanyl-Phenylalanyl) (cPhePhe) in the vapor phase, by means of photoemission spectroscopy and theoretical modeling. The last compound was evaporated from the solid linear dipeptide, but cyclised, losing water to form cPhePhe in the gas phase. The results are compared with our previous studies of three other cyclopeptides. Experimental valence and core level spectra have been interpreted in the light of calculations to identify the basic chemical properties associated with the central diketopiperazine ring, and with the additional functional groups. The valence spectra are generally characterized by a restricted set of outer valence orbitals separated by a gap from most other valence orbitals. The theoretically simulated core and valence spectra of all three cyclic dipeptides agree reasonably well with the experimental spectra. The central ring and the side chains act as independent chromophores whose spectra do not influence one another, except for prolyl dipeptides, where the pyrrole ring is fused with the central ring. In this case, significant changes in the valence and core level spectra were observed, and explained by stronger hybridization of the valence orbitals.     

新单取代苯磺酰脲衍生物的合成及生物活性

以较高活性的单取代苯磺酰脲为基础,设计合成了14个新的含烷硫基和烷胺基嘧啶环的单取代苯磺酰脲化合物,其结构经¹HNMR及元素分析确证.用油菜根长法测定IC₅₀,并进行盆栽除草活性测试,结果表明,嘧啶环4位取代基的变化对分子除草活性影响较大,活性大致按烷氧基、烷硫基和烷胺基的顺序递减.     

A convenient synthesis and structural analysis of novel 4,5,6,7-tetrahydro-1H-indazoles

A new series of t-4-aryl-3,c-6-dihydroxy-6-methyl-4,5,6,7-tetrahydro-1H-indazole-r-5-carboxylic acid isopropyl esters has been synthesized by adopting a conventional method from cyclic β-keto esters. ¹H, ¹³C NMR, and IR spectra for all the compounds were investigated. HMBC, HSQC, COSY, and NOESY spectra of the representative compounds were studied. The stereochemistry of a six-membered ring of the fused indazoles resembled that of keto esters. From the HMBC correlations the indazole structure was confirmed as 1H-indazole.