A new non-centrosymmetric material (C5H9N3)[ZnBr4]⸳H2O : Molecular structure, characterization, optical properties and biological activities

The use of 2,3-diaminopyridine as an aromatic organic molecule in the synthesis of a new hybrid halogenometallate compound by the slow evaporation method afforded an unexpected non-centrosymmetric structure type. The obtained material with the formula (C5H9N3)[ZnBr4]⸳H2O (1) crystallizes in the triclinic space group P1. The compound was characterized by UV-visible measurements, differential thermal analysis (TG-DTA), single crystal X-ray diffraction and nonlinear optical activity. The structure consists of isolated tetrahedral [ZnBr4]2− anions, 2-amino-3-ammoniopyridinium [C5H9N3]2+ cations and water molecules, which are connected via N-H…O/Br and O-H…Br hydrogen bonds leading to the formation and strengthening of a three-dimensional supramolecular assembly. The optical band gap and Urbach energy were obtained through Tauc's equation. The direct and indirect band gap values are found to be 3.23 and 3.55 eV, respectively. The bioassay results showed that the compound exhibits modest antibacterial and antifungal activities.