Photoelectrochromism in the Retinal Protonated Schiff Base Chromophore: Photoisomerization Speed and Selectivity under a Homogeneous Electric Field at Different Operational Regimes

The spectral tunability, photoisomerization efficiency and selectivity, of the native all-trans retinal protonated Shiff base (PSB) chromophore driven by a homogeneous electric field is systematically investigated. By analyzing the absorption wavelength dependence, charge distribution, and PES profi...

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Bibliographic Details
Published in:Journal of chemical theory and computation 2016-09, Vol.12 (9), p.4460-4475
Main Authors: El-Tahawy, Mohsen M. T, Nenov, Artur, Garavelli, Marco
Format: Article
Language:English
Subjects:
Charge distribution
Chromophores
Electric fields
Electricity
Electronic structure
Isomerism
Molecular Conformation
Near infrared radiation
Protons
Quantum Theory
Retinaldehyde - chemistry
Schiff Bases - chemistry
Selectivity
Spectra
Topography
Ultraviolet Rays
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Summary:The spectral tunability, photoisomerization efficiency and selectivity, of the native all-trans retinal protonated Shiff base (PSB) chromophore driven by a homogeneous electric field is systematically investigated. By analyzing the absorption wavelength dependence, charge distribution, and PES profiles along selected torsional angles, as well as the electronic structure, energetics, and topography of the CI seam in the presence of strong positive and negative electric fields, we recognize the existence of qualitatively/fundamentally different photophysics and photochemistry with respect to the unperturbed (i.e., absence of an electric field) chromophore. We rationalize the findings within the scope of molecular orbital theory and deliver a unified picture of the photophysics of the retinal PSB chromophore over a wide, even beyond the usually observed, spectral regime, ranging from the near-infrared to the ultraviolet absorption energies. This work has a 3-fold impact: a) it accounts for, and extends, previous theoretical studies on the subject; b) it delivers a rationale for the ES lifetimes observed in retinal proteins, both archeal and visual rhodopsins, as well as in solvent; and c) the transferability of the discovered trends on PSB mimics is demonstrated.
ISSN:1549-9618
1549-9626
DOI:10.1021/acs.jctc.6b00558