Visible-Light Photoswitching by Azobenzazoles
Journal article, 2020

Three visible-light responsive photoswitches are reported, azobis(1-methyl-benzimidazole) (1), azobis(benzoxazole) (2) and azobis(benzothiazole) (3). Photostationary distributions are obtained upon irradiation with visible light comprising approximately 80 % of the thermally unstable isomer, with thermal half-lives up to 8 min and are mostly invariant to solvent. On protonation, compound 1H+ has absorption extending beyond 600 nm, allowing switching with yellow light, and a thermal half-life just under 5 minutes. The two isomers have significantly different pKa values, offering potential as a pH switch. The absorption spectra of 2 and 3 are insensitive to acid, although changes in the thermal half-life of 3 indicate more basic intermediates that significantly influence the thermal barrier to isomerization. These findings are supported by high-level ab initio calculations, which validate that protonation occurs on the ring nitrogen and that the Z isomer is more basic in all cases.

visible light

azobenzene

photochromism

pH switch

photoswitch

Author

Aaron D.W. Kennedy

University of New South Wales (UNSW)

Isolde Sandler

University of New South Wales (UNSW)

Joakim Andreasson

Chalmers, Chemistry and Chemical Engineering, Chemistry and Biochemistry

Junming Ho

University of New South Wales (UNSW)

J. E. Beves

University of New South Wales (UNSW)

Chemistry - A European Journal

0947-6539 (ISSN) 1521-3765 (eISSN)

Vol. 26 5 1103-1110

Subject Categories

Theoretical Chemistry

DOI

10.1002/chem.201904309

PubMed

31729050

More information

Latest update

2/17/2020