A computational protocol for the study of circularly polarized phosphorescence and circular dichroism in spin-forbidden absorption

Maciej Kaminski, Janusz Cukras, Magdalena Pecul, Antonio Rizzoc, Sonia Coriani

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

We present a computational methodology to calculate the intensity of circular dichroism (CD) in spinforbidden absorption and of circularly polarized phosphorescence (CPP) signals, a manifestation of the optical activity of the triplet–singlet transitions in chiral compounds. The protocol is based on the response function formalism and is implemented at the level of time-dependent density functional theory. It has been employed to calculate the spin-forbidden circular dichroism and circularly polarized phosphorescence signals of valence n → p* and n ← p* transitions, respectively, in several chiral enones and diketones. Basis set effects in the length and velocity gauge formulations have been explored, and the accuracy achieved when employing approximate (mean-field and effective nuclear charge) spin–orbit operators has been investigated. CPP is shown to be a sensitive probe of the triplet excited state structure. In many cases the sign of the spin-forbidden CD and CPP signals are opposite. For the b,g-enones under investigation, where there are two minima on the lowest triplet excited state potential energy surface, each minimum exhibits a CPP signal of a different sign
Original languageEnglish
JournalPhysical Chemistry Chemical Physics
Volume17
Issue number29
Pages (from-to)19079-19086
Number of pages8
ISSN1463-9076
DOIs
Publication statusPublished - 2015
Externally publishedYes

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