Novel nonlinear optical crystals of noncentrosymmetric structure based on hydrogen bonds interactions between organic and inorganic molecules

For second harmonic generation (SHG), well-established inorganic crystals are now in direct competition with more efficient organic molecular crystals, made of highly polarizable conjugated molecules suitably packed to build up a noncentrosymmetrical structure. In recent years, a new strategy has been developed in material engineering, with intent to associate the strong quadratic nonlinear coefficients of some remarkable organic crystals to the mechanical and thermal stabilities of mineral structures, owing to the complexion of organic and inorganic molecules based on acid–base interactions. We present several hydrogen-bonded molecular crystals composed of various nonlinear organic molecules (cations) linked to the anions corresponding to phosphoric, selenic, orthoarsenic, and phenyloarsenic acids, respectively. SHG activity was measured using the Kurtz and Perry powder technique, crystal structure was determined from X-ray measurements, TF-IR and TF-Raman spectra were used to characterize the formation of hydrogen bonds.