SYNTHESIS AND CHARACTERIZATION OF NICKEL(II) AND COPPER(II) COMPLEXES WITH A TETRAPHENYL-DIBENZO TETRAAZACYCLOHEXENE MACROCYCLE: STRUCTURAL AND DNA BINDING STUDIES

DOI: https://doie.org/10.65985/jbse.2025572253

Rahul Kumar, Umendra Kumar

Keywords:

tetraaza macrocycle, nickel(II) complexes, copper(II) complexes, DNA binding, coordination geometry, EPR spectroscopy, ligand field parameters.

Abstract:

A novel tetraaza macrocyclic ligand, 6,8,15,17-tetra(4-chlorophenyl)dibenzo[b,i]-1,4,8,11 tetraazacyclotetradeca-1,3,5,7,9,11-hexaene, and its six nickel(II) and copper(II) complexes with chloro, nitrato, and sulphato axial ligands were synthesized under high-dilution conditions. Detailed spectroscopic analyses (UV-Vis, IR, ¹H-NMR, EPR) and magnetic susceptibility measurements revealed varied coordination geometries: octahedral for Ni(II) chloro and sulphato complexes; square planar for Ni(II) nitrato; tetragonal for Cu(II) chloro and nitrato; and square pyramidal for Cu(II) sulphato complexes. Ligand field parameters highlighted distinct electronic environments. Binding studies with calf thymus DNA showed intercalative or groove-binding interactions, with the square planar Ni(II) nitrato complex exhibiting the highest affinity. These findings emphasize the critical role of axial ligands in shaping the structural and biological properties of macrocyclic metal complexes, suggesting their potential in DNA-targeted bioinorganic applications.

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