量子化学计算辅助聚（N-异丙基丙烯酰胺）溶液碳谱的归属

波谱学杂志

量子化学计算辅助聚（N-异丙基丙烯酰胺）溶液碳谱的归属

刘松柏¹，陈群^1*，杨光¹，严晓虎²

1.华东师范大学分析测试中心，教育部光谱学与波谱学重点实验室，上海 200062; 2.南京大学化学系，南京 210093

收稿日期:2001-02-16 出版日期:2001-06-05 发布日期:2001-06-05
作者简介:刘松柏（1977-），男，硕士,E-mail: liulannet@hotmail.com.*通讯联系人
基金资助:
教育部全国高校百名优秀青年教师教学与科研奖励基金及上海市优秀学科带头人计划资助项目

¹³C HIGH-RESOLUTION SPECTRUM OF POLY(N-ISOPROPYLACRYLAMIDE) AS ASSIGNED WITH THE AID OF GAUSSIAN98 QUANTUM CHEMICAL CALCULATION

LIU Song-bai¹, CHEN Qun^1*, YANG Guang¹, YAN Xiao-hu²

1.Analytical Center and Key Laboratory of Educational Ministry for Optics and Magnetic Resonance, East China Normal University, Shanghai 200062; 2.Department of Chemistry, Nanjing University, Nanjing 210093

Received:2001-02-16 Online:2001-06-05 Published:2001-06-05
About author:*Corresponding author
Supported by:
教育部全国高校百名优秀青年教师教学与科研奖励基金及上海市优秀学科带头人计划资助项目

摘要/Abstract

摘要：

测定了聚（N-异丙基丙烯酰胺）（PNIPAAM）的溶液高分辨定量¹³C NMR谱，使用γ-gauche效应和Gaussian98从头计算GIAO-CHF两种方法分别计算了各立构序列的化学位移. 结果表明在计算结果与实验数据之间的符合程度方面，从头计算方法明显优于γ-gauche效应方法.利用从头计算的结果对谱图作了相应归属，并分析了PNIPAAM的立构规整度. 结果表明PNIPAAM链的增长服从Bernoulli过程，立构序列满足无规分布.这说明量化计算和NMR相结合是研究高分子高级链结构的有效方法.

关键词: 聚（N-异丙基丙烯酰胺）, 立构规整度, 化学位移计算

Abstract:

The quantitative ¹³C high resolution NMR spectrum of poly(N-isopropylacrylamide) (PNIPAAM) was assigned with the aid of Gaussian98 calculation. Two methods, γ-gauche effect and ab initio calculation, have been applied to calculate the ¹³C NMR chemical shifts of stereosequences of PNIPAAM. The parameters for γ-gaucheeffect were developed from the ab initio calculations of diads. The basis set used was 6-31G*, and the method was GIAO-CHF. For ab initio calculation, all geometries were optimized via AM1 method and the ¹³C NMR chemical shifts were calculated via GIAO-CHF method with STO-3G basis set. Stereosequences to triad level were considered for the methine carbon of main chain, while for the methylene and methyl carbons, stereosequences to tetrad and pentad level were considered respectively. It was found that the ab initio calculation can well reproduce the obse

rved ¹³C NMR spectrum, while the γ-gauche effect method failed to give satisfactory result. Thus, based on the result of ab initio calculation, the signals of m

ethine carbons, methylene carbon and methyl carbon were assigned and the tacticity of PNIPAAM was turn out to be random. As a result, the ab initio calculation was proved to be an effective method to investigate the tacticities of macromolecules.

Key words: Poly(N-isopropylacrylamide), Tacticity, Modeling NMR Chemical Shifts

中图分类号:

O641.13

刘松柏1，陈群1*，杨光1，严晓虎2. 量子化学计算辅助聚（N-异丙基丙烯酰胺）溶液碳谱的归属[J]. 波谱学杂志.

LIU Song-bai1, CHEN Qun1*, YANG Guang1, YAN Xiao-hu2. ¹³C HIGH-RESOLUTION SPECTRUM OF POLY(N-ISOPROPYLACRYLAMIDE) AS ASSIGNED WITH THE AID OF GAUSSIAN98 QUANTUM CHEMICAL CALCULATION[J]. Chinese Journal of Magnetic Resonance.

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