水溶液中稀土离子与甘氨酸、丝氨酸、天冬氨酸作用的~(13)C NMR研究

测定了酸性水溶液中甘氨酸、丝氨酸和天冬氨酸稀土络合物(Ln=La、Pr、Nd、Eu、Tb、Dy、Ho、Er、Tm和Yb)的~(13)C诱导位移。对位移试剂的分析指出,三种氨基酸通过α-羧基以双齿形式配位于稀土,配位键长为0.23nm～0.25nm,天冬氨酸的y-羧基也是配位基团。由本文与文献中已报道的各种氨基酸稀土络合物的~(13)C诱导位移的系统分析表明,配体~(13)C超精细偶合常数A值和结构因子G值有如下规律:(1)│A(C_0)│<│A(C_α)│;A(C_0)为正,A(C_α)为负;(2)│G(C_0)│>│G(C_α)│;配体碳核的G均为负值。

SEQUENCE STRUCTURE OF ETHYLENE-VINYL SUBSTITUTED COPOLYMER WITH C-13 NMR .4.

The substituent chemical shift (SCS) has been applied to the assignment of the C-13 NMR spectrum of chlorinated polyethylene (CPE). CPE of different chlorine contents has been employed and their sequence structure discussed. The results show that characteristic of CPE with medium chlorine content is the dichloroethane structure in molecular chain. SCS parameters have been obtained from the C-13 NMR spectra. It was found that the effects of chlorine content and temperature on SCS are negligible, but the substituent parameter S1 reduced by 0.39 ppm when C2Cl4 was added to solvent ODCB.

C-13 NMR CHARACTERIZATION OF SOLUBLE POLYANILINE

A high-resolution C-13 n.m.r. spectrum of soluble polyaniline in DMF-d7 solution was recorded. The assignment for the various resonance peaks in the spectrum was tentatively performed and the chain structure of polyaniline was analysed. It has been shown that the main chain of pristine state polyaniline is composed of alternating benzoid-quinoid and successive benzoid-quinoid sequences with the former being present in greater concentration. The sequence distribution is random. In addition to the benzoid-type and quinoid-type structures, there is a small amount of other structural units in the main chain.

SOLID-STATE C-13 NMR-STUDIES ON THE CONDENSATION AND SULFONATION OF FURFURYL ALCOHOL AND TRIS (2-HYDROXYETHYL) ISOCYANURATE

The condensation and sulfonation of furfuryl alcohol (FA) and FA with tris (2-hydroxyethyl) isocyanurate (THEIC) and the crosslinking product structures were studied by means of solid-state C-13 NMR. The reaction of formalin with FA linear oligomer terminated by 2-methyl furan took place in the presence of the phase transfer catalyst (C4H9)4N+I-. The reaction of the terminated oligomer with a large amount of sulfuric acid as well as the former reaction was examined. The effects of some main reaction conditions on the crosslinking condensation and sulfonation were also discussed.

C-13 AND H-1 NMR STUDIES OF SOLUTION STRUCTURE OF LANTHANIDE COMPLEX WITH GLYCYL-GLYCINE

C-13 and H-1 NMR technique was used to study the interaction of Gly-Gly with heavy lanthanide cations Dy3+, Ho3+, Er3+, Tm3+ and Yb3+ in aqueous solution. The stability constants for the 1:1 and 1:2 complexes of Gly-Gly with Ho3+ and Yb3+ were determined from the titration curves of chemical shift versus concentration ratio of lanthanide to Gly-Gly. The solution structure of the Ln-Gly-Gly complex was analyzed based upon the C-13 and H-1 lanthanide induced shifts and the results show that in the complex Gly Gly is coordinated to the lanthanide ion through the carboxyl oxygens with the backbone of the ligand in an extended state.

碳-13核磁共振定量测定萄葡糖及果糖的含量

本文利用~(13)C-NMR方法测量由葡萄糖通过葡萄糖异构酶的作用,在不同的条件下,在转化为果糖的过程中葡萄糖和果糖的相对含量。同时~(13)C-NMR技术也是直接测定各种构型糖含量的有效方法。实验结果表明,Gd-DPTA弛予试剂能够使自旋-晶格弛豫时间(T1)缩短。同时对NOE效应的消除也作了描述。本法测定的相对误差低于±0.5％。

水溶性聚合物和两亲聚合物 13.低分子量聚丙烯酸及其钠盐的合成

低分子量(<2×10~4)聚丙烯酸(PAA)及其钠盐有着日趋广泛的应用前景,包括用作工业水系统的除垢、防垢剂,金属材料的新型淬火剂及造纸工业中所用颜料的分散剂等。为此已发展了一些合成方法,如使用链转移剂、在异丙醇-水混合溶剂中聚合、用金属盐-

高分辨~(13)C NMR在聚合物辐射化学中的应用

综述了高分辨~(13)C核磁共振谱(~(13)C NMR)在聚合物辐射化学研究中的应用。重点介绍了用固体高分辨~(13)C NMR研究聚合物辐射交联结构途径和应用范围。

双甘肽稀土配合物溶液结构的~(13)C~1H NMR研究

关于双甘肽的~(13)C化学位移行为及其与稀土离子的配位作用前人有过报导。但有关水溶液中双甘肽稀土配合物的结构仍不清楚。本文测定了在重稀土离子Dy~(3+)、Ho~(3+)、Er~(3+)、Tm~(3+)和Yb~(3+)作用下双甘肽~(13)C和~1H的顺磁诱导位移,研究了水溶液中双甘肽稀土配合物的组成及结构。1 实验部分

固体~(13)C NMR研究呋喃醇和呋喃醇与三-(2-羟乙基)-异氰酸尿酯缩聚磺化反应

用固体~(13)C NMR研究了呋喃醇(FA)和FA与三-(2-羟乙基)-异氰酸尿酯(THEIC)缩聚磺化反应及其产物结构,考察了2-甲基呋喃封端的FA线型齐聚物与甲醛水溶液在相转移催化剂(C_4H_9)_4N~+I~-和与大量硫酸作用下的反应特点,探讨了主要参数对反应的影响,阐明了缩聚交联磺化反应的规律,确定了产物的结构。

CAMOS:人工智能结构解析 Ⅳ应用化学信息和碳-13谱分析亚结构集合

本文介绍在CAMOS系统中应用化学信息和碳-13谱图信息进行亚结构集合分析的方法.这些方法可以有效地筛选除不符合未知物信息的候选亚结构集合,降低结构生成过程中的组合度,避免冗余结构的生成,从而使整个系统效率提高.程序采用人机会话方式进行,可在小型或微型计算机上运行.

CAMOS:人工智能结构解析 Ⅴ碳-13 NMR谱用于结构确认

本文介绍在CAMOS系统中应用碳-13 NMR谱确认候选结构的方法.将候选结构的模拟谱与未知物实验谱进行比较,可以推测候选结构的可信度.其方法有谱峰个数比较、化学位移比较及波谱相似度计算,已得到满意的结果.程序用FORTRAN 77语言编写,可在小型机或微机上运行.

光活性聚甲基丙烯酸三苯甲酯链结构的研究——PTrMA的~(13)C液体和固体NMR谱

80年代出现的光活性高聚物—聚甲基丙烯酸三苯甲酯(PTrMA)是由非手性单体经不对称阴离子聚合得到的。近年来,PTrMA作为手性固定相在分离手性化合物方面得到了越来越多的实际应用。由于聚合物侧基上的三个苯基产生的大位阻,使它具

电子计算机自动结构解析专家系统研究——带有键属性的亚结构与~(13)C—NMR化学位移相关性

本文系统地介绍了利用~(13)C-NMR数据库系统统计法建立带有键属性亚结构与~(13)C-NMR化学位移相关表(结构解析专家系统的约束知识库的一个组成部分)的过程。在亚结构的选择上作了深入的探讨。在亚结构检索上提出了加权码值计算方法。