Issue 35, 2015

Retinal shows its true colours: photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base

Abstract

Retinal is one of Nature's most important and widespread chromophores, exhibiting remarkable versatility in its function and spectral response, depending on its protein environment. Reliable spectroscopic and photochemical data for the isolated retinal molecule are essential for calibrating theoretical approaches that seek to model retinal's behaviour in complex protein environments. However, due to low densities and possible co-existence of multiple isomers, retinal is a challenging target for gas-phase investigations. Here, the photoisomerization behaviour of the trans isomer of the retinal protonated Schiff base (RPSB) is investigated in the gas phase by irradiating mobility-selected RPSB ions with tunable light in a tandem ion mobility spectrometer. trans RPSB ions are converted to single cis isomers and also more compact isomers through irradiation with visible light. The S1 ← S0 photoisomerization action spectrum of trans RPSB, obtained by monitoring production of cis isomers as a function of wavelength, exhibits a single well-defined peak with a maximum at 618 ± 5 nm. Corresponding action spectra of cis RPSB isomers exhibit broader peaks, conclusively demonstrating an isomeric dependence for the RPSB spectrum in the gas phase.

Graphical abstract: Retinal shows its true colours: photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base

Supplementary files

Article information

Article type
Paper
Submitted
22 Jun 2015
Accepted
05 Aug 2015
First published
05 Aug 2015
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2015,17, 22623-22631

Author version available

Retinal shows its true colours: photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base

N. J. A. Coughlan, B. D. Adamson, L. Gamon, K. Catani and E. J. Bieske, Phys. Chem. Chem. Phys., 2015, 17, 22623 DOI: 10.1039/C5CP03611A

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