Third-order electric susceptibility of nonpolar azimuthal molecular rotors mounted on a covalent polymer grid

Polyacene molecules are constrained to rotate about the principal axis associated with the diagonal component of the molecular polarizability tensor that is intermediate in size. The rotation axes are oriented vertically ('azimuthal rotors') and are attached to a covalent monolayer grid such as that recently reported in the literature. We calculate the value of the relevant component of the third-order electric susceptibility of the system for a variety of grid spacings and determine that the optical nonlinearity of such a system is not particularly large, at best approaching that of carbon disulfide.