An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds

• DOI: 10.1073/pnas.0802376105
• Publication Date: 2008-11-12T01:45:21Z
• Authors: Adalgisa Sinicropi; Elena Martin; Mikhail Ryazantsev; Jan Helbing; Julien Briand; Divya Sharma; Jérémie Léonard; Stefan Haacke; Andrea Cannizzo; Majed Chergui; Vinicio Zanirato; Stefania Fusi; Fabrizio Santoro; Riccardo Basosi; Nicolas Ferré; Massimo Olivucci
• Keywords: 10120 Department of Chemistry; Time Factors; Photochemistry; UV-vis; Molecular modeling; Molecular switches; Simulation and Modeling (artificial mol. switch mimics visual pigment and completes photocycle in picoseconds); Isomerization (photoisomerization; artificial mol. switch mimics visual pigment and completes photocycle in picoseconds); Pigments (visual; artificial mol. switch mimics visual pigment and completes photocycle in picoseconds); 01 natural sciences; Isomerism; 540 Chemistry; Spectroscopy, Fourier Transform Infrared; 0103 physical sciences; mid-IR; photochemical switch; 1000 Multidisciplinary; photochemical switch; time resolved spectroscopy; [SCCO.NEUR]Cognitive science/Neuroscience; [SCCO.NEUR] Cognitive science/Neuroscience; Molecular Mimicry; mol switch vision pigment photocycle isomerization; 0104 chemical sciences; time resolved spectroscopy; CASPT2//CASSCF; Spectrophotometry, Ultraviolet; CASPT2//CASSCF; mid-IR; photochemical switch; time resolved spectroscopy; UV-vis; Retinal Pigments

Single molecules that act as light-energy transducers (e.g., converting the energy of a photon into atomic-level mechanical motion) are examples of minimal molecular devices. Here, we focus on a molecular switch designed by merging a conformationally locked diarylidene skeleton with a retinal-like Schiff base and capable of mimicking, in solution, different aspects of the transduction of the visual pigment Rhodopsin. Complementary ab initio multiconfigurational quantum chemistry-based computations and time-resolved spectroscopy are used to follow the light-induced isomerization of the switch in methanol. The results show that, similar to rhodopsin, the isomerization occurs on a 0.3-ps time scale and is followed by <10-ps cooling and solvation. The entire (2-photon-powered) switch cycle was traced by following the evolution of its infrared spectrum. These measurements indicate that a full cycle can be completed within 20 ps.