Synthesis, crystal structures, and quadratic nonlinear optical properties in a series of pushpull boronate derivatives

A series of eighteen new pushpull molecules obtained by self-assembly of salicylideniminophenols and various phenylboronic acids is reported. Electric field-induced second-harmonic measurements of the nonlinear optical response reveal that the nature of the phenylboron moieties has a modest influence on the molecular hyperpolarizabilities (?). The crystal data available suggest the possibility of easy rotation of the phenyl substituents, with an energy barrier around 10 kcal mol?1, while a computational investigation conducted at the semi-empirical (INDO) level leads to a prediction of 30% ?-modulation occuring upon the rotation.