Unraveling the Mechanism of Photoinduced Charge Transfer in Carotenoid-Porphyrin-C60 Molecular Triad.
Photoinduced charge transfer (CT) plays a central role in biologically significant systems and in applications that harvest solar energy. We investigate the relationship of CT kinetics and conformation in a molecular triad. The triad, consisting of carotenoid, porphyrin, and fullerene is structurally flexible and able to acquire significantly varied conformations under ambient conditions. With an integrated approach of quantum calculations and molecular dynamics simulations, we compute the rate of CT at two distinctive conformations. The linearly extended conformation, in which the donor (carotenoid) and the acceptor (fullerene) are separated by nearly 50 Å, enables charge separation through a sequential CT process. A representative bent conformation that is entropically dominant, however, attenuates the CT, although the donor and the acceptor are spatially closer. Our computed rate of CT at the linear conformation is in good agreement with measured values. Our work provides unique fundamental understanding of the photoinduced CT process in the molecular triad.
†Department of Chemistry, Kent State University, 1787 Summit Street, Kent, Ohio 44242, United States.
Arun K
AK
Manna
∥Computation Institute, University of Chicago, 5735 South Ellis Avenue, Chicago, Illinois 60637, United States.
D
D
Balamurugan
§Center for Theoretical Biological Physics, Rice University, 6500 Main Street, Houston, Texas 77030, United States.
Margaret S
MS
Cheung
†Department of Chemistry, Kent State University, 1787 Summit Street, Kent, Ohio 44242, United States.
Barry D
BD
Dunietz
D002338:Carotenoids / Q000737:chemistry*; D004579:Electron Transport; D037741:Fullerenes / Q000737:chemistry*; D008968:Molecular Conformation; D056004:Molecular Dynamics Simulation; D011166:Porphyrins / Q000737:chemistry*; D012993:Solar Energy
C558421:C60-porphyrin; D037741:Fullerenes; D011166:Porphyrins; D002338:Carotenoids
molecular dynamics; molecular triad; organic photovoltaic; photoinduced charge transfer; range-separated hybrid functional; solvation