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

TY - JOUR

T1 - Retinal shows its true colours

T2 - Photoisomerization action spectra of mobility-selected isomers of the retinal protonated Schiff base

AU - Coughlan, N. J.A.

AU - Adamson, B. D.

AU - Gamon, L.

AU - Catani, K.

AU - Bieske, E. J.

PY - 2015/8/5

Y1 - 2015/8/5

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=84940434565&partnerID=8YFLogxK

U2 - 10.1039/c5cp03611a

DO - 10.1039/c5cp03611a

M3 - Journal article

C2 - 26280514

AN - SCOPUS:84940434565

SN - 1463-9076

VL - 17

SP - 22623

EP - 22631

JO - Physical Chemistry Chemical Physics

JF - Physical Chemistry Chemical Physics

IS - 35

ER -