Abstract：A theoretical study on the polyamic acid (PAA) and its derivatives with different side chain (GPAA1-4) by semi-empirical PM3 is presented in this paper. After optimization, the authors get their balanceable geometric configurations. For all optimal geometric configurations, there is no imaginary frequency in vibrational analysis, which proves that the geometric configurations are stable. On this basis, the electronic spectra have been calculated by a single-excitation configuration interaction (CIS) method. Tie calculated results are consistent with experimental values on the whole. The authors found that the fluorescence intensity of polyamic acid (PAA) with p-π conjugation side chain is enhanced obviously, and the longer the alkyl side chain the more intense the fluorescence will be. This will help us to design and synthesize the polymer fluorescence material.
[1] WANG Lun, WANG Xue-qin(王 伦，王雪芹). Journal of Anhui Normal University(Natural Science)(安徽师范大学学报·自然科学版), 1994, 17(1): 38. [2] WANG Xue-jie, YE Shuai-guan(王学杰, 叶率官). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 1994, 14(2): 25. [3] SU Yu, LIAO Xian-wei, LI Shu-wei, LIANG Xiao-qin, ZOU Qin, LI Hui(苏 宇，廖显威，李树伟, 梁晓琴, 邹 勤, 李 辉). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2003, 23(1): 137. [4] LIANG Xiao-qin, SU Yu, LIAO Xian-wei(梁晓琴，苏 宇，廖显威). Chinese Journal of Atomic and Molecular Physics(原子与分子物理学报)，2001, 18(2): 210. [5] Alen K Y, Jen Kevin, Drost J, et al. J. Chem., Chem. Commun., 1994: 965. [6] LU Qing-hua, LI Mei, TAO Ping, et al(路庆华，李 梅，陶 萍, 等). Journal of Shanghai Jiaotong University(上海交通大学学报), 2001, 35(4): 605. [7] XU Guang-xian, LI Le-min, WANG De-min(徐光宪，黎乐民，王德民). Quantum Chemistry Fundamental Principle and <i>Ab initio</i> Method(Middle)(量子化学基本原理和从头计算方法, 中册). Beijing: Science Press(北京：科学出版社), 1985.
