Crystalline molecular machines: a quest toward solid-state dynamics and function.

Complex molecular machinery may be envisioned as densely packed, multicomponent, self-assembling systems built with high structural precision to control the dynamics of one or more internal degrees of freedom. With molecular gyroscopes as a test, we describe a general strategy to design crystals capable of supporting structurally programmed molecular motions, a practical approach to their synthesis, convenient strategies to characterize their solid-state dynamics, and potential applications based on polar structures responding collectively to external fields.