Synthesis, physico-chemical studies, non-linear optical properties and DFT calculations of a new non-centrosymmetric compound: (3-ammoniumpyridinium)tetrachloridozincate (II)

A new non-linear optical inorganic–organic hybrid material [H 3 NCH 2 (C 4 H 4 NH)]ZnCl 4 (3-ampH 2 )ZnCl 4 ) has been synthesized and characterized by single-crystal X-ray diffraction, thermal analysis and UV–visible absorption. The compound crystallizes in the non-centrosymmetric orthorhombic space group Cmc2 1 allowing in principle non-linear optical properties. The structure consists of (3-ampH 2 ) 2+ cations disordered in two possible orientations stabilized through Coulombic and hydrogen-bond interactions with isolated ZnCl 42− anions. Intermolecular weak π-π stacking interactions are also observed between pyridine rings. The thermal analysis indicate that (3-ampH 2 )ZnCl 4 starts to melt at 585 K, together with the beginning of its decomposition. UV–visible measurements shows that the material is transparent in a wide range of UV–visible region with a lower cut off wavelength of 261.65 nm. The wide range of transparency in the UV–visible region and the high decomposition temperature make of (3-ampH 2 )ZnCl 4 a good candidate for NLO application. Density functional theory (DFT) calculations indicate that the first-order hyperpolarizability β tot is about 23.38 times more than that of Potassium Dihydrogen Phosphate. (3-ampH 2 )ZnCl 4 is a potential good NLO material.