Ab Initio Study of Phosphorescence of Hetero[8]Circulenes

• Published in: Russian physics journal Vol. 62; no. 3; pp. 406 - 410
• Main Authors: Valiev, R. R., Baryshnikov, G. V., Cerepanov, V. N., Sundholm, D.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.07.2019; Springer; Springer Nature B.V
• Subjects: Circulenes; Comparative analysis; Condensed Matter Physics; Coupling (molecular); Germanium; Hadrons; Heavy Ions; Internal conversion; Lasers; Mathematical analysis; Mathematical and Computational Physics; Nuclear Physics; Optical Devices; Optics; Organic chemistry; Phosphorescence; Photonics; Physics; Physics and Astronomy; Quantum chemistry; Silicon; Spin coupling; Spin-orbit interactions; Theoretical; Wave functions; heterocirculenes; quantum chemistry; phosphorescence; circulenes; oxygen; photodynamic therapy
• ISSN: 1064-8887; 1573-9228
• DOI: 10.1007/s11182-019-01727-7

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 τ phos 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 T 1 and S 0 by virtue of heavier Ge atoms as compared to Si. The τ phos 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 T 1 and S 0 owing to simultaneous spin-orbit and nonadiabatic interaction of their wavefunctions.