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Strong Duschinsky Mixing Induced Breakdown of Kasha's Rule in an Organic Phosphor
L PAUL, T MOITRA, K RUUD, S CHAKRABARTI
Published in American Chemical Society
2019
Volume: 10
   
Issue: 3
Pages: 369 - 374
Abstract
We present the novel observation that Duschinsky mixings can lead to the breakdown of Kasha's rule in a white light phosphor molecule, dibenzo[b,d]thiophen-2-yl (4-chlorophenyl)methanone. Our theoretical analyses show the energy gap between the T 1 and T 2 states (0.48 eV) is too large to allow for any significant population of the T 2 state at room temperature and instead the faster intersystem crossing (ISC) between the S 1 and T 2 states is rather due to strong Duschinsky mixing, leading to the emission from the T 2 state as well. A second-order cumulant-based method has been used for the calculation of the ISC rate, which suggests 2 orders of magnitude faster ISC rates for S 1 ? T 2 compared to those for S 1 ? T 1 . We found that the carbonyl moiety of the S 1 and T 2 states of the molecule is significantly different with respect to bond angle and dihedral angles, engendering large displacements in selective normal modes, thus giving rise to strong Duschinsky mixing. Copyright © 2019 American Chemical Society.
About the journal
JournalData powered by TypesetJournal of Physical Chemistry Letters
PublisherData powered by TypesetAmerican Chemical Society
ISSN1948-7185
Open AccessYes