A Schiff base ligand containing thiocarbamide group of 4-phenyl-1-(4-methoxyl-1-phenylethylidene)thiosemicarbazide (HL) and its three mononuclear metal complexes of ZnL 2 (1), NiL 2 (2), and CuL 2 (3) have been synthesized. Elemental analysis, IR, and X-ray single crystal diffraction characterizations for the ligand and the three complexes have been carried out. In the three complexes, the central metallic ions of Zn 2? , Ni 2? , and Cu 2? coordinate with two deprotonated ligands of L -, respectively. In 1, Zn 2? ion adopts a distorted tetrahedral geometry, while in 2 and 3, both the Ni 2? and Cu 2? ions possess distorted square planar configurations. For the four compounds, UV-Vis spectra have been measured and DFT calculations at B3LYP/LANL2DZ level of theory prove that the electronic spectra of HL and 1 are corresponding with electronic transitions of n ? p* and p ? p* in the ligand itself and the electronic spectra of 2 and 3 are attributed to intraligand electronic transitions as well as d-d electronic transitions. Electrochemical investigations reveal that the different metal-ligand interactions have changed the peak shapes and peak locations, which are corresponding with the DFT-B3LYP/LANL2DZ calculational results. Fluorescence spectra measurements indicate that the ligand emits purple fluorescence and the complex 1 emits stronger blue fluorescence, while the complexes 2 and 3 quench fluorescence. The thermal analyses result show that the three complexes undergo two similar decomposition processes because of their similar geometric configurations.

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