Synthesis, spectral and antimicrobial studies of a novel macrocyclic ligand containing a piperazine moiety and its binuclear metal complexes

A novel macrocycle 1,16-diaza-7,10-diamino-6,11-dioxo-1,17-bis[20-hydroxy-5'-aminobenzyl]-piperazine- 4,12-cyclododecadiene, [H4L] has been synthesized by a multistep process. The interaction of 5-amino salicylic acid, piperazine and formaldehyde in ethanol gave PC-1, which was reduced into a chloro-derivative PC-2. PC-2 by reacting with ethylenediamine gave a new macrocyclic ligand titled [H4L]. Its binuclear complexes with Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) ions have also been synthesized. The ligand and all metal complexes have been characterized by elemental analysis, IR, H-1 NMR, C-13 NMR and U.V. Visible spectroscopy. Molar conductance and magnetic moment measurements have also been determined. Microanalytical data revealed 1 : 2 molar ratio of ligand to metal in all the complexes. The spectral and magnetic data indicate that Mn(II), Co(II), Ni(II) complexes show octahedral geometry with two water molecules while Cu(II) and Zn(II) complexes exhibit square planar and tetrahedral environments, respectively. The compounds show significant inhibitory activity against seven bacteria and seven fungi.