Computational design of a light-driven imine-based motor with bulky chiral stator

Abstract

A light-driven imine-based motor with bulky chiral stator has been computationally designed by investigation of the topographical features of the potential energy surfaces. The electronically excited model imine with a P-helical trans form directly goes to the conical intersection (CIX) in S1 on the downhill surface with respect to the CN torsion. After electronic relaxation into S0 around CIX with a double cone topography, the model imine goes to another P-helical cis-imine without any trap in the M-helical region through the CN torsion. Thereby, the full rotary process of the imine-based motor consists of two fast photochemical steps of (P)-trans → (P)-cis and (P)-cis → (P)-trans, which is possible to realize smooth rotation by repetitive photoexcitation, unlike the previous imine-based motors with four chemical steps. In addition, the other full rotary cycle with two steps is also open, of which latter-half process of (P)-cis → (P)-trans is the slow thermal N-inversion.