Acta Chimica Sinica ›› 2007, Vol. 65 ›› Issue (10): 894-898. Previous Articles     Next Articles

Original Articles

低聚1,4-苯乙烯撑及其衍生物的结构和吸收光谱的理论研究

王继芬*,1,2, 封继康*,2, 徐金球1   

  1. (1上海第二工业大学环境工程系 上海 201209)
    (2吉林大学理论化学研究所 理论化学计算国家重点实验室 长春 130023)
  • 投稿日期:2006-11-13 修回日期:2006-12-08 发布日期:2007-05-28
  • 通讯作者: 封继康

Theoretical Studies of Structures and Absorption Spectra of the Oligomers of 1,4-Phenylene Vinylene and Their Derivatives

WANG Ji-Fen*,1,2; FENG Ji-Kang*,2; XU Jin-Qiu1   

  1. (1 Department of Environmental Engineering, Shanghai Second Polytechnic University, Shanghai 201209)
    (2 State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023)
  • Received:2006-11-13 Revised:2006-12-08 Published:2007-05-28
  • Contact: FENG Ji-Kang

The structures of oligomers (PV)n (PV=1,4-phenylene vinylene, n=2~8) and (PVSD)n (PVSD= 2-(1,4-phenylene vinylene)-10-vinylene-spirocyclohexane-1,6-dibenzo[d,f](1,3)dioxepin, n=1~4) were optimized by B3LYP/6-31G. The structures of (PV)n (n=2~8) tend to be coplanar, with the dihedral angles of no larger than 1°. (PVSD)n (n=1~4) are twisted in seven-membered-rings, with large dihedral angles about 38° between phenyl rings. The relations between the HOMO-LUMO gaps of oligomers and their chain length were analyzed on the basis of the optimized structures. This relationship is useful to study optical properties of their polymers. The ZINDO and TD-DFT were also used to study the energy gaps. To the importance, the absorption spectra were obtained by both means. The polymeric absorption wavelengths were estimated by extrapolating those of the oligomers to the inverse of chain length to zero. The effective conjugation length was obtained during extrapolation. The result shows that the twisted structure of (PVSD)n (n=∞) breaks the conjugation length. It has broader energy band than that of (PV)n (n=∞), that is, the absorption band was blue shifted.

Key words: 1,4-phenylene vinylene, density functional theory, optimization, absorption spectrum