1-(3-Chlorophenyl)-4-(3-phenylseleno propyl) piperazine (L); synthesis, spectroscopic characterization, DFT studies, antimicrobial evaluation and its reactivity toward group 12 metal chlorides

C6H5Se-Na+ (generated in situ by NaBH4 reduction of (C6H5Se)(2)) on reaction with ClC3H6C4H8N2ClC6H5 under N-2 atmosphere results in C6H5SeC3H6C4H8N2ClC6H5 (L) as a cream-colored solid. Its 1:1 metal complexes having the general formula [MLX2], where M = Zn, Cd, Hg, and X 1/4 Cl, have been prepared. Ligand L and its complexes 1-3 are characterized on the basis of physico-chemical and spectral (FT-IR, ESI Mass, H-1, C-13, DEPT 135 degrees C-13 {1H}, and 77Se{1H} NMR) studies. IR spectroscopy revealed that L is coordinated solely through selenium and nitrogen to zinc, cadmium, and mercury ions forming a six-membered chelate ring around M(II) ions. Elemental analysis measurements along with H-1, C-13, DEPT 135 degrees C-13{H-1}, and ESI-mass data also confirm the bidentate coordination mode of the ligand. Moreover, the coordination from selenium atom is also supported by the downfield shift of signal in Se-77{H-1} NMR spectroscopy. Using DFT-based optimization of structures, the HOMO-LUMO energy gaps and molecular electrostatic potential surface of ligand L and complexes 1-3 were theoretically calculated at the B3LYP/LANL2DZ level of theory. Ligand L and complexes 1-3 display significant antibacterial and antifungal activity.