Excited-State Aromaticity Improves Molecular Motors: A Computational Analysis.

A new approach to the design of more efficient light-driven rotary molecular motors is presented and evaluated computationally based on molecular dynamics simulations. The approach involves enabling part of the motor to become aromatic in the photoactive excited state, and is found to sharply increase the rotary quantum yields of the photoisomerizations that underlie the motor function. Excited-state aromaticity thus holds promise as a guiding principle toward better-performing molecular motors.