Preparation and Spectral and Biological Investigation of vic-Dioxime Ligands Containing Piperazine Moiety and Their Mononuclear Transition-Metal Complexes

Two vic-dioxime ligands, N-(4-benzylpiperazine-1-yl) p-tolylglyoxime (L¹H₂) and N,N′-bis(4-benzylpiperazine-1-yl) glyoxime (L²H₂), containing piperazine moieties were synthesized, and their Ni(II), Cu(II), Co(II) and Zn(II) complexes were obtained. The ligands were characterized by elemental analysis, Fourier transform–infrared (FT-IR), ultraviolet–visible NMR (¹H, ¹³C, and heteronuclear multiple-bond correlation), and electrospray ionization (ESI) mass spectrometry. The isolated complexes were characterized by a combination of elemental analysis, IR, UV-vis, and ESI mass spectrometry and in the case of Ni(II) and Zn(II) complexes by ¹H and ¹³C NMR spectroscopy. The electrochemical behaviors of the ligands and their complexes were studied by cyclic voltammetry (CV) in dimethylsulfoxide solution containing tetrabutylammoniumtetrafluoroborate (TBATFB). The antibacterial activity was also studied against S. aureus ATCC 25923, S. aureus ATCC 29213, S. mutans RSHM 676, E. faecalis ATCC 29212, E. coli ATCC 25922, and P. aeruginosa ATCC 27853. The antimicrobial test results indicated that all the compounds have good antibacterial activity against P. auriginosa ATCC 27853 bacteria and were as effective as ampicilin.

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