Photoisomerization of Protonated Azobenzenes in the Gas Phase

Michael S. Scholz, James N. Bull, Neville J.A. Coughlan, Eduardo Carrascosa, Brian D. Adamson, Evan J. Bieske

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Abstract

Because of their high photoisomerization efficiencies, azobenzenes and their functionalized derivatives are used in a broad range of molecular photoswitches. Here, the photochemical properties of the trans isomers of protonated azobenzene (ABH+) and protonated 4-aminoazobenzene (NH2ABH+) cations are investigated in the gas phase using a tandem ion mobility spectrometer. Both cations display a strong photoisomerization response across their S1 ↔ S0 bands, with peaks in their photoisomerization yields at 435 and 525 nm, respectively, red-shifted with respect to the electronic absorption bands of the unprotonated AB and NH2AB molecules. The experimental results are interpreted with the aid of supporting electronic structure calculations considering the relative stabilities and geometries of the possible isomers and protomers and vertical electronic excitation energies.

Original languageEnglish
Pages (from-to)6413-6419
Number of pages7
JournalJournal of Physical Chemistry A
Volume121
Issue number34
DOIs
Publication statusPublished - 3 Aug 2017

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