A Light-Gated Molecular Brake with Antilock and Fluorescence Turn- On Alarm Functions: Application of Singlet-State Adiabatic Cis →Trans Photoisomerization

摘要

A light-gated molecular brake that displays both high braking power (～10~7) and high switching power (～74%) is reported. The lower rate for brake-on than for brake-off switching of the pentiptycene rotor mimics the function of an antilock braking system (ABS) for vehicles on a loose surface. The brake is also armed with a fluorescence turn-on alarm for accidental deactivation of the ABS function by acids. All of these features are associated with the highly efficient singlet-state adiabatic cis → trans photoisomerization of the phenylstilbene chromophore.