Ab Initio Study of Phosphorescence of HeteroCirculenes
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Quantum chemical calculations of phosphorescence lifetime are performed for the first time by ab initio CC2 and TD-DFT methods for heterocirculenes bearing Si and Ge atoms. According to the results of calculations, a lower value of τphos for tetragermatetrathiacirculene (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 tetrasilatetrathiacirculene (I) and tetragermatetrathiacirculene (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.
Keywordscirculenes heterocirculenes oxygen quantum chemistry photodynamic therapy phosphorescence
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- 6.M. Casida, Recent Advances in Density Functional Methods. Part I, World Scientific, Singapore (1999).Google Scholar
- 10.DALTON, http://daltonprogram.org.
- 12.TURBOMOLE V7.2 2017; http://www.turbomole.com.
- 14.P. W. Atkins and R. Friedman, Molecular Quantum Mechanics, Oxford University Press (2005).Google Scholar