Issue 11, 2018

Effect of thiophene substitution on the intersystem crossing of arene photosensitizers

Abstract

The effect of thienyl substitution on the intersystem crossing (ISC) of a few arenes was studied using steady state and time-resolved transient absorption and emission spectroscopies, as well as DFT/TDDFT computations. We found that the phenyl and thienyl substituents generally induce red-shifted absorptions for the chromophores, and the DFT/TDDFT computations show that the red-shifted absorption and emission are due to the increased HOMO and the reduced LUMO energy levels. Nanosecond transient absorption spectra indicate the formation of a triplet state, the triplet state lifetime is up to 282 μs, and the singlet oxygen quantum yields (ΦΔ) are up to 60%. DFT/TDDFT computations indicate that introducing the thienyl substituent alters the relative singlet/triplet excited state energy levels, and the energy level-matched S1/T2 states are responsible for the enhanced ISC of the thienyl compounds. This information is useful for the design of heavy atom-free triplet photosensitizers and for the study of the fundamental photochemistry of organic compounds.

Graphical abstract: Effect of thiophene substitution on the intersystem crossing of arene photosensitizers

Supplementary files

Article information

Article type
Paper
Submitted
05 jun 2018
Accepted
21 aug 2018
First published
21 aug 2018

Photochem. Photobiol. Sci., 2018,17, 1794-1803

Effect of thiophene substitution on the intersystem crossing of arene photosensitizers

F. Sadiq, J. Zhao, M. Hussain and Z. Wang, Photochem. Photobiol. Sci., 2018, 17, 1794 DOI: 10.1039/C8PP00230D

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