Crystal structure, vibrational spectra and nonlinear optical properties of L-histidinium-L-tartrate hemihydrate

Single crystals of a new L-histidinium salt: L-histidinium L-tartrate hemihydrate, [(C3H4N2)+C3H6NO2].(C4H5O6)(-).0.5H(2)O, were obtained by slow evaporation of an aqueous solution at room temperature. The compound crystallises in a noncentrosymmetric space group of the monoclinic system. The L-histidine molecule occurs in the zwitterion form, with additional protonation of the N(3) ring atom, while the tartaric acid is singly ionised with one COO- carboxylate group. The vibrational spectra are in full agreement with the structure obtained from X-ray crystallography. The salt is a good second harmonic generator: the SHG efficiency was measured as d(eff) = 0.79d(eff) (KDP). (C) 2003 Elsevier B.V. All rights reserved.