Fulgides as Light-Driven Molecular Rotary Motors: Computational Design of a Prototype Compound

A new
family of light-driven molecular rotary motors utilizing
the fulgide motif is proposed and its prototype molecule is studied
by quantum chemical calculations and nonadiabatic molecular dynamics
simulations. The new motor performs pure unidirectional axial rotation
of the rotor blade with high quantum efficiency (ϕ ∼
0.55–0.68) and ultrafast dynamics (⟨t⟩S1 ∼ 200–300
fs) of its successive photoisomerization steps. The photocyclization
reaction typical of fulgide compounds is blocked by the design of
the new motor and never occurred in the molecular dynamics simulations.
The new motors can be synthesized from easily available precursors.
In view of its remarkable photoisomerization ability, the new motor
represents a prospective class of compounds for the use in nanosized
molecular devices.