Enhancing optical absorbance and accelerating rotational speed in molecular motors through oriented external electric fields.

Accelerating the rotational speed of light-driven molecular motors is among the foremost concerns in molecular machine research, as this speed directly influences the performance of a motor. Controlling the motor's rotation is crucial for practical applications, and using an oriented external electric field (OEEF) represents a feasible method to achieve this objective. We have investigated the impact of an OEEF on the optical and kinetic properties of a novel π-donor/acceptor di-substituted molecular motor, R2,3-(NH2, CHO). We employed density functional theory (DFT) and time-dependent DFT methods to analyze the electronic excitation and thermal isomerization behavior. Our results demonstrate that the absorption wavelength, absorption efficiency of the motor, and rate constant of the thermal isomerization reaction can be adjusted by applying OEEFs, which are predictable based on the dipole moment and polarizability of the molecules under consideration. In particular, we observed a shift in the absorption wavelength toward longer ranges, an enhancement in light absorption intensity, and an acceleration in the rotation rate when applying a weak positive directional external electric field to the R2,3-(NH2, CHO) motor. In summary, this theoretical study highlights the potential of OEEFs for improving the performance of molecular motors.