Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (6): 781-787.DOI: 10.6023/A22010056 Previous Articles     Next Articles



王珞聪, 李哲伟, 岳彩巍, 张培焕, 雷鸣*(), 蒲敏*()   

  1. 北京化工大学化工资源有效利用国家重点实验室 计算化学研究所 化学学院 北京 100029
  • 投稿日期:2022-01-30 发布日期:2022-07-07
  • 通讯作者: 雷鸣, 蒲敏
  • 基金资助:

Theoretical Study on the Isomerization Mechanism of Azobenzene Derivatives under Electric Field

Luocong Wang, Zhewei Li, Caiwei Yue, Peihuan Zhang, Ming Lei(), Min Pu()   

  1. State Key Laboratory of Chemical Resource Engineering, Institute of Computational Chemistry, College of Chemistry, Beijing University of Chemical Technology, Beijing 100029, China
  • Received:2022-01-30 Published:2022-07-07
  • Contact: Ming Lei, Min Pu
  • Supported by:
    National Natural Science Foundation of China(22073005)

In this paper, the trans-cis isomerization mechanism of azobenzene derivative 2'-p-tolyldiazenyl-1,1':4,4'- terphenyl-4,4''-dicarboxylic acid (TTDA) under different electric field intensity was calculated and studied by symmetry destruction density functional theory (DFT). There are three possible isomerization modes of TTDA through C—N1=N2 angle trans-cis isomerization (N2 connected to large substituents and N1 connected to small substituents in azo groups), inversion around N1 or N2 atoms and rotation around N1=N2 bonds. The calculation results show that the electric field can significantly reduce the energy barrier of isomerization reaction. After adding the electric field, the electrons in trans-TTDA molecule have obvious transfer, the π orbit is polarized, and the energy level difference of HOMO (highest occupied molecular orbital) and LUMO (the lowest unoccupied molecular orbital) is significantly reduced, which also shows that the trans configuration of TTDA molecule is easier to convert to cis configuration. When the forward electric field along the z axis is added (taking the C1→C2 direction as the positive direction of the z axis), the rotation path is the optimal path. The rotation isomerization pathway around the N=N bond owns a lower free energy barrier compared to the inversion pathways. The steric effect is more important than the electrostatic effect for the isomerization of TTDA under the electric field along the C1→C2 direction. In addition, we also studied adding an electric field along the N=N bond (taking the N2→N1 direction as the positive direction of the z axis). When the electric field intensity is 0.00 V•Å-1, the inversion barrier of N1 is higher than that of N2. When –0.62 V•Å-1Fz≤0.93 V•Å-1, the rotation path is the dominant path. When –0.93 V•Å-1Fz≤–0.62 V•Å-1, N2 inversion path is the dominant path. When Fz≤–1.03 V•Å-1, the terphenyl of cis-TTDA along the N2→N1 direction is deformed. The molecular polarizability increases with the increase of electric field intensity. The electric field greatly promotes electron transfer in the isomerizaiton of TTDA as well as their electronic structures.

Key words: electric field, azobenzene derivatives, isomerization, reaction mechanism, density functional theory