SPIN-ORBIT INTERACTIONS IN ORTHO-ARYL-SUBSTITUTED CORROLES AND PORPHYRINS

UDC 535.34+541.65

  • Kruk Mikalai Mikalaevich – DSc (Physics and Mathematics), Professor, Head of the Department of Physics. Belarusian State Technological University (13a, Sverdlova str., 220006, Minsk, Republic of Belarus). E-mail: m.kruk@belstu.by

DOI: https://doi.org/10.52065/2520-6141-2023-266-1-6

Keywords: porphyrin, corrole, spin-orbit interactions, ortho-aryl-substitution, intersystem crossing.

For citation: Kruk M. M. Spin-orbit interactions in ortho-aryl-substituted corroles and porphyrins. Proceedings of BSTU, issue 3, Physics and Mathematics. Informatics, 2023, no. 1 (266), pp. 29–33. DOI: https://doi.org/10.52065/2520-6141-2023-266-1-6.

Abstract

The regularities of spin-orbit interactions caused by the attachment of aryl groups with orthosubstituted halogen atoms to the Cm-positions of the tetrapyrrolic macrocycle of the free base corroles and porphyrins have been studied in this work. The relationship between the intersystem crossing rate constant kST and the sum of the spin-orbit coupling constants squared Σζ2 of halogen atoms was analyzed. It has been established that the internal heavy atom effect, caused by halogen atoms, in porphyrins leads to two-fold increase in the rate of the intersystem crossing growth as compared to corroles. It is proposed that this is due to significant differences in the energy gap between the lowest excited singlet S1 and triplet T1 states ΔE(S1–T1). The same spin-orbit perturbation leads to larger changes in the intersystem crossing rate constant kST in case of smaller energy gap. The correlation found can be used to estimate the energy of the lowest triplet T1 state in the homologous series of tetrapyrrolic compounds differing in the architecture of peripheral substitution, and for this one need to know only the photophysical characteristics of the lowest excited singlet S1 state.

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26.12.2022