Dielectric response of a dipolar molecular rotor crystal

We report the results of the dynamics of a three dimensional lattice of dipolar molecular rotors where the unit cells consist of a dipolar phenylene ring rotating about an axle stabilized by stationary triphenyl groups. The molecules are synthesized such that the lattice may be customized to elicit novel and useful physical phenomena. Using dielectric spectroscopy and H-2 NMR, we demonstrate rapid thermal rotation of the molecular rotors in the solid state, and characterize the depth and asymmetry of the rotational potential. Calculations show that rotor-rotor interactions are weak in this structure, and the rotational potential is dominated by steric interactions between each rotary element and the nonrotating portions of neighboring molecules.