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 language | English |
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Pages (from-to) | 406-410 |
Number of pages | 5 |
Journal | Russian Physics Journal |
Volume | 62 |
Issue number | 3 |
DOIs | |
Publication status | Published - 15 Jul 2019 |
Keywords
- circulenes
- hetero[8]circulenes
- oxygen
- phosphorescence
- photodynamic therapy
- quantum chemistry
ASJC Scopus subject areas
- Physics and Astronomy(all)