Physical and Analytical Chemistry Seminar
Lecturer: Prof. Igor Schapiro
Location: Faculty Seminar Room
The primary event of vision in the vertebrate eye is the highly selective and efficient photoisomerization of 11-cis-retinal protonated Schiff base (RPSB) bound to the visual protein rhodopsin (Rh). With a ~100% selectivity, ~65% quantum yield, and ~200 fs product appearance time, this isomerization is considered the archetype of a photochemical reaction optimized by nature to achieve a specific molecular response.
Recently, we have used a combination of a quantum chemical and a classical force field method (QM/MM) to resolve the isomerization mechanism for the RPSB chromophore in Rh. Important stereoelectronic factors were found that determine the outcome of the photoisomerization. The same protocol was also applied to investigate the photochemical mechanism of the newly discovered Anabaena Sensory Rhodopsin and of a biomimetic molecular switch that works in solution.
Using the same computational protocol we have also studied the ground state (thermal) isomerization. The results of the simulations explain the molecular mechanism of thermal noise in rod photoreceptors and make a direct link to experimentally found correlations for night vision.
 Schapiro I, Ryazantsev M N, Frutos L M, Ferré N, Lindh R, Olivucci M. J. Am. Chem. Soc. (2011), 133, 3354.
 Schapiro I, Ruhman S. Biochim Biophys Acta. (2014), 1837, 589.
 Léonard J, Schapiro I, Briand J, Fusi S, Paccani R R, Olivucci M, Haacke S. Chem. Eur. J. (2012), 18, 15296.
 Gozem S, Schapiro I, Ferré N, Olivucci M. Science (2012), 33, 6099. This study provides important design rules for new, more stable and efficient materials for photovoltaic applications.