Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (05): 1085-1093.doi: 10.3866/PKU.WHXB201203024


Electronic Absorption Spectra of Meso-Substituted Porphyrins and Their Zinc Derivatives

CAO Zhen-Feng, CHEN Qi-Bin, LU Yun-Xiang, LIU Hong-Lai, HU Ying   

  1. Key Laboratory for Advanced Material and Development of Chemistry, East China University of Science and Technology, Shanghai 200237, P. R. China
  • Received:2011-12-12 Revised:2012-02-29 Published:2012-04-26
  • Contact: CHEN Qi-Bin
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20806025, 21103047) and National 111 Project of China's Higher Education (B08021).

Abstract: Meso-substituted porphyrin derivatives have demonstrated great potential as sensing materials for toxic gas detection. In this paper, density functional theory (DFT) and its time-dependent DFT approach (TD-DFT) were employed to investigate the ultraviolet-visible (UV-Vis) or the near-ultravioletvisible (near-UV-Vis) absorption spectra of Meso-tetra (o-nitrophenyl/o-aminophenyl) porphyrins (NO2PP, NH2PP) and their corresponding zinc derivatives, NO2ZnPP and NH2ZnPP. The geometry optimizations for these four molecules were obtained from two different exchange-correlation functionals, the generalizedgradient approximation functional PBE (Perdew-Burke-Ernzerhof) and the hybrid functional B3LYP (Becke, three-parameter, Lee-Yang-Parr). The excitation energies and oscillation strengths were obtained from TD-DFT calculations. Calculations show that the optical absorptions are associated with numerous electronic transitions. In addition, the PBE-predicted wavelengths of the B and Q bands are more consistent with experiment than those predicted by B3LYP. The B band of NO2-substituted derivative exhibits a bathochromic shift different from that of NH2-containing material, also consistent with experimental results. In addition, at the PBE/6-31G(d) level of theory, the calculated energies of the lowest triplet excited states of NO2PP, NH2PP, NO2ZnPP, and NH2ZnPP are 1.426, 1.469, 1.608, and 1.581 eV, respectively.

Key words: TD-DFT, Electronic absorption spectrum, Electronic transition, Bathochromic shift, Triplet state