Synthesis, characterization and photophysical studies of zinc(II) complexes derived from a hydralazine hydrazone

In the present study, we report two novel mononuclear zinc(II) complexes (1 and 2) obtained by reacting (E)-1-(phenyl(pyridin-2-yl)methylene)-2-(phthalazin-1-yl)hydrazine (L) with ZnCl₂ and Zn(NO₃)₂∙6H₂O respectively. Photophysical properties of the compounds were studied in both solution and solid phase. The fluorescence absolute quantum yield of the complexes in solution varies in the order 1 (0.01) < 2 (0.030), on the other hand in the solid state it varies in the order 2(0.034) < 1(0.69). Quenching of fluorescence intensity of 2 in the solid-state has been attributed to intense and extensive non-covalent interactions present in the crystal structure. Theoretical calculations, density functional theory (DFT) and time- dependent density functional theory (TD-DFT) were also performed to support the experimental findings.