SCI和EI收录∣中国化工学会会刊

中国化学工程学报 ›› 2020, Vol. 28 ›› Issue (2): 532-540.DOI: 10.1016/j.cjche.2019.07.008

• Energy, Resources and Environmental Technology • 上一篇    下一篇

A DFT and TD-DFT study on electronic structures and UV-spectra properties of octaethyl-porphyrin with different central metals (Ni, V, Cu, Co)

Xiaoqin Wang1, Shiyi Li2, Liang Zhao2, Chunming Xu2, Jinsen Gao2   

  1. 1 College of Science, China University of Petroleum (Beijing), Beijing 102249, China;
    2 State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing), Beijing 102249, China
  • 收稿日期:2018-12-26 修回日期:2019-07-03 出版日期:2020-02-28 发布日期:2020-05-21
  • 通讯作者: Liang Zhao
  • 基金资助:
    The authors acknowledge the supports from the National Natural Science Foundation of China (21822810, 21476260, and 21838011), and are grateful to Quan Shi professor in the State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing).

A DFT and TD-DFT study on electronic structures and UV-spectra properties of octaethyl-porphyrin with different central metals (Ni, V, Cu, Co)

Xiaoqin Wang1, Shiyi Li2, Liang Zhao2, Chunming Xu2, Jinsen Gao2   

  1. 1 College of Science, China University of Petroleum (Beijing), Beijing 102249, China;
    2 State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing), Beijing 102249, China
  • Received:2018-12-26 Revised:2019-07-03 Online:2020-02-28 Published:2020-05-21
  • Contact: Liang Zhao
  • Supported by:
    The authors acknowledge the supports from the National Natural Science Foundation of China (21822810, 21476260, and 21838011), and are grateful to Quan Shi professor in the State Key Laboratory of Heavy Oil Processing, China University of Petroleum (Beijing).

摘要: In this work, the octaethyl-porphyrins with different central metals (M-OEP, M=Ni, VO, Cu, Co) were used to investigate the ground-state molecular structure, electron distribution and UV-spectra properties on molecular level by density functional theory (DFT). The results showed that the calculation structure parameters of metalloporphyrins agreed well with the experimental value. According to the Natural Bond Orbital (NBO) analysis, the charge distribution of different metalloporphyrins was found that the charge values of the central metal M decreased with the order of VO < Ni < Co < Cu, while the bonding strength between M and the coordinating atom N was VO > Ni > Co > Cu. At the same time, the frontier molecular orbital calculations showed that the SOMO energy of VO (OEP) molecules in the open-shell system was higher than that of Co (OEP) and Cu (OEP), which means that its UV absorption characteristic peak would be red-shifted. In addition, the IEFPCM model of Time-dependent Density functional theory (TD-DFT) was further utilized to simulate the four substance in toluene solution: Co (OEP), Ni (OEP), Cu (OEP) and VO (OEP), and the Soret band peaks were calculated respectively as: 382 nm, 383 nm, 391 nm and 401 nm. Furthermore, the quantitative simulation analysis of metalloporphyrins was combined with experimental data. It could be found that the location rules of the four kinds of metalloporphyrins calculated absorption characteristic peaks were consistent with the experimental ones, and the relative errors of each peak were within 3%. These methods used above provide a theoretical path for analyzing and identifying unknown porphyrin compounds in petroleum.

关键词: Metallic impurity, Metalloporphyrin, Asphaltenes, Quantum chemistry, UV-vis spectrum

Abstract: In this work, the octaethyl-porphyrins with different central metals (M-OEP, M=Ni, VO, Cu, Co) were used to investigate the ground-state molecular structure, electron distribution and UV-spectra properties on molecular level by density functional theory (DFT). The results showed that the calculation structure parameters of metalloporphyrins agreed well with the experimental value. According to the Natural Bond Orbital (NBO) analysis, the charge distribution of different metalloporphyrins was found that the charge values of the central metal M decreased with the order of VO < Ni < Co < Cu, while the bonding strength between M and the coordinating atom N was VO > Ni > Co > Cu. At the same time, the frontier molecular orbital calculations showed that the SOMO energy of VO (OEP) molecules in the open-shell system was higher than that of Co (OEP) and Cu (OEP), which means that its UV absorption characteristic peak would be red-shifted. In addition, the IEFPCM model of Time-dependent Density functional theory (TD-DFT) was further utilized to simulate the four substance in toluene solution: Co (OEP), Ni (OEP), Cu (OEP) and VO (OEP), and the Soret band peaks were calculated respectively as: 382 nm, 383 nm, 391 nm and 401 nm. Furthermore, the quantitative simulation analysis of metalloporphyrins was combined with experimental data. It could be found that the location rules of the four kinds of metalloporphyrins calculated absorption characteristic peaks were consistent with the experimental ones, and the relative errors of each peak were within 3%. These methods used above provide a theoretical path for analyzing and identifying unknown porphyrin compounds in petroleum.

Key words: Metallic impurity, Metalloporphyrin, Asphaltenes, Quantum chemistry, UV-vis spectrum