Blueprint for Crystalline Materials Exhibiting Correlated Molecular Rotational Dynamics and Emergent Properties

Correlated molecular rotation in crystalline solids represents a frontier in the design of artificial molecular machines. Unlike isolated environments in solution, crystalline lattices provide a unique platform where steric interactions, packing geometries, and symmetry constraints can enforce collective motion reminiscent of gear-like mechanisms. Recent advances have revealed how intermolecular correlations can propagate motion beyond single units in the crystalline solid state. This perspective reviews emerging strategies for engineering correlated molecular dynamics in the solid state, examines representative systems, and outlines prospects for translating molecular gearing into functional crystalline materials.