Behind the scenes of spin-forbidden decay pathways in transition metal complexes

Torsha Moitra, Pijush Karak, Sayantani Chakraborty, Kenneth Ruud*, Swapan Chakrabarti

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


The interpretation of the ultrafast photophysics of transition metal complexes following photo-absorption is quite involved as the heavy metal center leads to a complicated and entangled singlet-triplet manifold. This opens up multiple pathways for deactivation, often with competitive rates. As a result, intersystem crossing (ISC) and phosphorescence are commonly observed in transition metal complexes. A detailed understanding of such an excited-state structure and dynamics calls for state-of-the-art experimental and theoretical methodologies. In this review, we delve into the inability of non-relativistic quantum theory to describe spin-forbidden transitions, which can be overcome by taking into account spin-orbit coupling, whose importance grows with increasing atomic number. We present the quantum chemical theory of phosphorescence and ISC together with illustrative examples. Finally, a few applications are highlighted, bridging the gap between theoretical studies and experimental applications, such as photofunctional materials.

Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Publication statusAccepted/In press - 2021

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