Studies on structure, NLO properties of a new organic NLO crystal: guanidinium 3,5-dihydroxybenzoate

A new organic nonlinear optical (NLO) crystal, guanidinium 3,5-dihydroxybenzoate (GDH), was synthesized and grown by solvent evaporation technique. The crystal structure was determined by single crystal X-ray diffraction. Noncovalent interaction analysis and molecular electrostatic potential analysis were conducted which found the structure is stabilized by strong hydrogen bond network, π–π interaction, and electrostatic interactions. The obtained GDH crystal was characterized by using FTIR, Raman, UV–Vis-NIR spectra, TG/DTA, and DSC. GDH crystal shows good transparency of about 95% in the entire NIR region. Furthermore, systematic theoretical DFT calculations at B3LYP level including HOMO–LUMO analysis, static polarizability, and hyperpolarizability density analysis were carried out. The results suggest that GDH crystal is a promising third order NLO material.