Single methylation at position C10of 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 S1and covalent S2states, reducing the excited-state lifetime by favoring the formation of a S1transient 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 S1state as well as the interaction with the covalent S2excited 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.
Fine Tuning of Retinal Photoinduced Decay in Solution / Demoulin, Baptiste; Altavilla, SALVATORE FLAVIO; Rivalta, Ivan; Garavelli, Marco. - In: THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS. - ISSN 1948-7185. - STAMPA. - 8:18(2017), pp. 4407-4412. [10.1021/acs.jpclett.7b01780]
Fine Tuning of Retinal Photoinduced Decay in Solution
Altavilla, Salvatore Flavio;Rivalta, Ivan;Garavelli, Marco
2017
Abstract
Single methylation at position C10of 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 S1and covalent S2states, reducing the excited-state lifetime by favoring the formation of a S1transient 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 S1state as well as the interaction with the covalent S2excited 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.