Synthesis, structural Characterization, Cyclic Voltammetric and Antibecterial Studies of Tetraaza 13-Membered Macrocyclic Copper(II), NIckel(II), Cobalt(II) and Zinc(II) Complexes DErived from the Schiff Base 3-Salicylidene-2,4-di(imino-4'-antipyrinyl)pe

Atetraaza macrocyclic Schiff base (L), synthesized from the Schiff base 3-salicylidene- 2,4-di(imino-4_-antipyrinyl)pentane (3SDAP) and o-phenylenediamine, acts as a tetradentate ligand to form cationic solid complexes with Cu(II), Ni(II), Co(II) and Zn(II) metal salts in ethanol. All the synthesized complexes were characterized by microanalytical data, magnetic susceptibility measurements, IR, UV-Vis, 1H-NMR, 13C-NMR, ESR and mass spectral techniques. The IR and UV-Vis spectral data and magnetic susceptibility values of the complexes suggest that the [CuL]Cl2, [NiL]Cl2, [CoL]Cl2 and [ZnL]Cl2 complexes exhibit square-planar geometry. The electrolytic behaviour and monomeric nature of the chelates were confirmed from their molar conductance data and magnetic susceptibility values respectively. Cyclic voltammetric data of copper complex in DMSO reveal that the unusual oxidation states such as Cu(I) and Cu(0) are stabilized by the ligand system. The cyclic voltammogram of the nickel(II) complex was also recorded in DMSO solution and the salient features are reported. The X-band ESR spectra of the copper complex in DMSO solution at 300 K and 77 K were recorded and their spin Hamiltonian parameters were calculated. The in vitro biological screening effects of the investigated compounds were tested against some microorganisms. The metal complexes have higher activity than the free ligand and the standard.