Chem. J. Chinese Universities ›› 2021, Vol. 42 ›› Issue (3): 767.doi: 10.7503/cjcu20200736

• Physical Chemistry • Previous Articles     Next Articles

Transient Absorption and Decay Kinetic Properties of Photo-excited Metal Coordinated Tetraphenylporphyrin

MA Zihui2, WANG Mengyan2, CAO Hongyu1(), TANG Qian1, WANG Lihao2, ZHENG Xuefang1()   

  1. 1.College of Life Science and Biotechnology
    2.College of Environmental and Chemical Engineering,Dalian University,Dalian 116622,China
  • Received:2020-10-08 Online:2021-03-10 Published:2021-03-08
  • Contact: CAO Hongyu E-mail:caohongyu@dlu.edu.cn;dlxfzheng@126.com

Abstract:

The naturally selected chlorophyll and heme, and zinc or nickel coordinated porphyrin photosensitizer showed excellent photochemical and photophysical properties. Photoexcitation of metalloporphyrin to the excited state is the first step of reaction, which is the research priorities and challenges. The classical template molecules of porphyrins tetraphenylporphyrin(TPP-2H), and four metal-coordinated tetraphenylporphyrins, TPP-FeCl, TPP-Ni, TPP-Mg and TPP-Zn, were chosen for the investigations of their photochemical and photophysical properties. The Soret band absorption peak intensities of photoexcited TPP-2H, TPP-Zn and TPP-Mg decreased significantly in steady state absorption spectrum, while the counterpart peak of TPP-Ni increased obviously from 0.3 a.u. to 1.3 a.u.. However, the peak location and intensity of TPP-FeCl remained almost the same. According to the transient absorption spectrum, the Soret band negative peaks of TPP-2H, TPP-Mg and TPP-Zn had the negativeΔOD values for the lower molar absorption coefficient εt than εG of ground state compounds. The positive and negative absorption peaks microsecond lifetime decay kinetics of TPP-2H, TPP-Mg and TPP-Zn confirmed the relatively stable transient excited states after the photoexcitation. All the experimental and theoretical data manifested that the unoccupied orbitals and electron distribution of metal ion in the center of porphyrins would induce the diversification of porphyrin photochemical and photophysical properties. The experimental research further assists to comprehend photosynthesis process and provides an important basis for the selection of coordination metal in the porphyrin application research field of photoelectric conversion.

Key words: Metalloporphyrin, Photoexcitation, Transient absorption spectrum, Decay kinetics, Electronic transfer

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