title: Computational Design of a Family of Light-Driven Rotary Molecular Motors with Improved Quantum Efficiency.
abstract: Two new light-driven molecular rotary motors based on the N-alkylated indanylidene benzopyrrole frameworks are proposed and studied using quantum chemical calculations and nonadiabatic molecular dynamics simulations. These new motors perform pure axial rotation, and the photochemical steps of the rotary cycle are dominated by the fast bond-length-alternation motion that enables ultrafast access to the S1/S0 intersection. The new motors are predicted to display a quantum efficiency higher than that of the currently available synthetic all-hydrocarbon motors. Remarkably, the quantum efficiency is not governed by the topography (peaked versus sloped) of the minimum-energy conical intersection, whereas the S1 decay time depends on the topography as well as on the energy of the intersection relative to the S1 minimum. It is the axial chirality (helicity), rather than the point chirality, that controls the sense of rotation of the motor.
authors.affiliation: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Nikiforov
authors.affiliation: Institute of Technical and Macromolecular Chemistry, RWTH Aachen University , Worringerweg 1, 52074 Aachen, Germany.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Gamez
authors.affiliation: Max-Planck-Institut für Kohlenforschung , Kaiser-Wilhelm-Platz 1, D-45470 Mülheim an der Ruhr, Germany.
authors.forename: Walter
authors.initials: W
authors.lastname: Thiel
authors.affiliation: Department of Chemistry, Southern Methodist University , 3215 Daniel Avenue, Dallas, Texas 75275-0314, United States.|Department of Chemistry, School of Natural Sciences, Ulsan National Institute of Science and Technology (UNIST) , Ulsan 689-798, Korea.
authors.forename: Michael
authors.initials: M
authors.lastname: Filatov
keywords: computational quantum chemistry; conical intersection; nonadiabatic dynamics; photoisomerization; unidirectional rotation