Ab Initio Study of Phosphorescence of Hetero[8]Circulenes

R. R. Valiev, G. V. Baryshnikov, V. N. Cerepanov, D. Sundholm

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Abstract

Quantum chemical calculations of phosphorescence lifetime are performed for the first time by ab initio CC2 and TD-DFT methods for hetero[8]circulenes bearing Si and Ge atoms. According to the results of calculations, a lower value of τphos for tetragermatetrathia[8]circulene (II) originates from two factors: almost 29 times more distorted main macrocycle II and almost four times larger spin-orbit coupling matrix element between T1 and S0 by virtue of heavier Ge atoms as compared to Si. The τphos values calculated by CC2 ideally agree with its experimental value; the difference is less than 2 and 0.3 s for tetrasilatetrathia[8]circulene (I) and tetragermatetrathia[8]circulene (II) molecules, respectively. The agreement of the lifetimes calculated by TD-DFT is only within an order of magnitude. The main intramolecular decay channel of the T1 state is internal conversion between T1 and S0 owing to simultaneous spin-orbit and nonadiabatic interaction of their wavefunctions.

Original languageEnglish
Pages (from-to)406-410
Number of pages5
JournalRussian Physics Journal
Volume62
Issue number3
DOIs
Publication statusPublished - 15 Jul 2019

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Keywords

  • circulenes
  • hetero[8]circulenes
  • oxygen
  • phosphorescence
  • photodynamic therapy
  • quantum chemistry

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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