Theoretical study on the working mechanism and computational evidence of robust imine-based light-driven molecular motor

We report quantum chemical calculations of two kinds of N-alkyl imine-based light-driven rotary motors by using time-dependent density functional theory. A new transition structure was found in the thermal isomerization. Based on the latter, we present a '3-step' rotation process and reveal the full working mechanism in the ground state. Furthermore, we theoretically verified the robustness of the motors through pendant group substitution of the rotator in the fjord region. As a result, the free-energy barriers of the rate-limiting thermal steps are capable to hold their robustness, which makes these motors more promising in potential machine fabrication at mo-lecular level.

Automated summary

We performed quantum chemical calculations using time-dependent density functional theory on two types of N-alkyl imine-based light-driven rotary motors. A new transition structure was discovered during thermal isomerization. Based on this, we proposed a '3-step' rotation process and revealed the complete working mechanism in the ground state. Additionally, we theoretically confirmed the robustness of the motors by substituting pendant groups on the rotator in the fjord region. The results showed that the free-energy barriers of the rate-limiting thermal steps can maintain their robustness, making these motors more promising for potential molecular-level machine fabrication.