间位聚苯及其衍生物的构象与电子结构的理论研究

1. 吉林大学超分子结构与材料教育部重点实验室，长春　130012
• 收稿日期:2004-05-20 修回日期:2004-08-02 发布日期:2004-12-15
• 通讯作者: 马於光 E-mail:ygma@mail.jlu.edu.cn

A Theoretical Investigation of Conformation and Electronic Structure of Poly(m-phenylene) and Its Derivatives

Yang Bing; Zhang Hai-Quan; Xu Hai; Zheng Yan; Yu Jing-Sheng; Ma Yu-Guang; Shen Jia-Cong

1. Key Laboratory for Supermolecular Structure and Materials of Ministry of Education, Jilin University, Changchun　130012
• Received:2004-05-20 Revised:2004-08-02 Published:2004-12-15
• Contact: Ma Yu-Guang E-mail:ygma@mail.jlu.edu.cn

Abstract: Potential energy of poly(m-phenylene)(PMP, P1) and the related derivatives (P2,P3) as a function of torsion angles(f) were constructed by using molecular mechanics method based on force field(Drieding 2.11). It is found that there are four minima in potential energy curve, which correspond to four torsion angles (f ≈－135°, －45°, 135°, 45°) respectively. Furthermore, all constructed PMP and derivatives are minimized by molecular force field, and four main conformations are found. For PMP, two helical conformations have minimal energy, and they have preponderant population. Under the real conditions, PMP and derivatives polymer chain may consist of above stable conformation segments with an equilibrium ratio, which depends on polymer surroundings. The electronic structure (HOMO-LUMO gap) prediction depending on torsion angles was calculated by GGA-DFT method using Dmol3 program. The AM1 method was used to investigate geometry optimization, and the optimized conformations are basically consistent with that simulated by molecular mechanics. In order to get more accurate HOMO-LUMO gap of above optimized geometries, the hybrid functional B3LYP was adopted at the level of 6-31G basis set using Gaussian98 software. At last, it is found that the twist extent of torsion angle between phenyl rings is the main factor that affects HOMO-LUMO gap of PMP and its derivatives.