1 research outputs found
Fine Tuning of Retinal Photoinduced Decay in Solution
Single methylation
at position C<sub>10</sub> of the all-trans
retinal protonated Schiff base switches its excited-state decay in
methanol from a slower picosecond into an ultrafast, protein-like
subpicosecond process. QM/MM modeling in conjunction with on-the-fly
excited-state dynamics provides fundamental understanding of the fine-tuning
mechanics that “catalyzes” the photoinduced decay of
solvated retinals. Methylation alters the interplay between the ionic
S<sub>1</sub> and covalent S<sub>2</sub> states, reducing the excited-state
lifetime by favoring the formation of a S<sub>1</sub> transient fluorescent
state with fully inverted bond lengths that accounts for the recorded
transient spectroscopy and from which a space-saving conical intersection
seam is quickly (<1 ps) reached. Minimal and apparently innocent
chemical modifications thus affect the characteristic intramolecular
charge-transfer of the S<sub>1</sub> state as well as the interaction
with the covalent S<sub>2</sub> excited state, eventually providing
the high tunability of retinal photophysics and photochemistry and
delivering a new concept for the rational design of retinal-based
photoactive molecular devices