Issue 36, 2023

Design rules for optimization of photophysical and kinetic properties of azoarene photoswitches

Abstract

Azoarenes are an important class of molecular photoswitches that often undergo EZ isomerization with ultraviolet light and have short Z-isomer lifetimes. Azobenzene has been a widely studied photoswitch for decades but can be poorly suited for photopharmacological applications due to its UV-light absorption and short-lived Z-isomer half-life (t1/2). Recently, diazo photoswitches with one or more thiophene rings in place of a phenyl ring have emerged as promising candidates, as they exhibit a stable photostationary state (98% EZ conversion) and E-isomer absorption (λmax) in the visible light range (405 nm). In this work, we performed density functional theory calculations [PBE0-D3BJ/6-31+G(d,p)] on 26 hemi-azothiophenes, substituted with one phenyl ring and one thiophene ring on the diazo bond. We calculated the E-isomer absorption (λmax) and Z-isomer t1/2 for a set of 26 hemi-azothiophenes. We compared their properties to thiophene-based photoswitches that have been studied previously. We separated the 26 proposed photoswitches into four quadrants based on their λmax and t1/2 relative to past generations of hemi-azothiophene photoswitches. We note 8 hemi-azothiophenes with redshifted λmax and longer t1/2 than previous systems. Our top candidate has λmax and a t1/2 approaching 360 nm and 279 years, respectively. The results here present a pathway towards leveraging and optimizing two properties of photoswitches previously thought to be inversely related.

Graphical abstract: Design rules for optimization of photophysical and kinetic properties of azoarene photoswitches

Supplementary files

Article information

Article type
Paper
Submitted
21 Aug 2023
Accepted
23 Aug 2023
First published
23 Aug 2023

Org. Biomol. Chem., 2023,21, 7351-7357

Author version available

Design rules for optimization of photophysical and kinetic properties of azoarene photoswitches

D. M. Adrion and S. A. Lopez, Org. Biomol. Chem., 2023, 21, 7351 DOI: 10.1039/D3OB01298K

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