Molecular dynamic crystals conveniently
combine flexibility required
for mechanical reconfiguration, strength for effective translation
of elastic energy, and long-range order of mechanically coupled molecules
for rapid conversion of disordered motion (heat) or photons (light)
into ordered motion (work). By direct measurement of the actuation
force generated by crystals of a thermosalient solid, here we describe
the first direct quantification of the work performed and energy
conversion that can be accomplished by using dynamic crystals as supramolecular
actuators. Upon reversible α-to-γ phase transition, crystals
of (phenylazophenyl)palladium hexafluoroacetylacetonate of submillimeter
to millimeter size exert forces in the range of 1–100 mN upon
longitudinal and lateral expansion. This work translates to a volumetric
power density of about 1–3 MW m–3 and
efficiency comparable to the existing multicomponent actuators.