Copper(II) and nickel(II) complexes of an N-pendent bis-(cyanoethyl) derivative of an isomeric hexamethyl tetraazamarocyclic ligand: Synthesis, characterization, electrolytic behavior and antimicrobial studies

Abstract

Hexamethyl derivative salt of the fourteen membered tetraazamacrocycle, Me6[14]diene.2HClO4 (L.2HClO4) has been synthesized by the condensation of ethylenediamine with acetone in presence of quantitative amount of perchloric acid. This diene ligand salt on reduction with NaBH4 followed by extraction with CHCl3 at pH above 12 resulted in a mixture of isomeric ligands, Me6[14]anes which were separated by fractional crystallization from xylene and designated by ‘tet-a’ and ‘tet-b’. Interaction of ‘tet-b’ with excess of acrylonitrile yielded an N-pendent derivative ‘tet-bx’ in which two cyanoethyl groups were attached on less crowded two trans-N atoms. Interactions of nickel(II) acetate tetrahydrate and copper(II) perchlorate hexahydrate with ‘tet-bx’ followed by subsequent addition of NaClO4·6H2O and HClO4 in case of nickel(II) produced square planar orange [Ni(‘tet-bx’)](ClO4)2 and six coordinated octahedral reddish purple [Cu(‘tet-bx’)(ClO4)2] complex respectively. The axial addition reactions on [Ni(‘tet-bx’)](ClO4)2 with NCS, NO3, NO2, Cl, Br and I afforded different colored six coordinated octahedral axial addition products: violet [Ni(‘tet-bx’)(NCS)2]; violet [Ni(‘tet-bx’)(NO3)(ClO4)]; green [Ni(‘tet-bx’)(NO2)(H2O)](ClO4); brown [Ni(‘tet-bx’)(ClO4)Cl]; brown [Ni(‘tet-bx’)(H2O)Br](ClO4) and pink [Ni(‘tet-bx’)(ClO4)I] respectively. All compounds have been characterized by different analytical and spectroscopic parameters. The antimicrobial activities of the concerned ligand and its complexes have been investigated against different bacteria and fungi.