Structural studies and anticancer activity of a novel (N6O4) macrocyclic ligand and its Cu(II) complexes

A novel (N6O4) macrocyclic ligand (L) and its Cu(II) complexes have been prepared and characterized by elemental analysis, spectral, thermal (TG/DTG), magnetic, and conductivity measurements. Quantum chemical calculations have also been carried out at B3LYP/6-31+G(d,p) to study the structure of the ligand and one of its complexes. The results show a novel macrocyclic ligand with potential amide oxygen atom, amide and amine nitrogen atoms available for coordination. Distorted square pyramidal ([Cu(L)Cl]Cl center dot 2.5H(2)O (1), [Cu(L)NO3]NO3 center dot 3.5H(2)O (2), and [Cu(L)Br]Br center dot 3H(2)O (4) and octahedral ([Cu(L)(OAc)(2)]center dot 5H(2)O (3)) geometries were proposed. The EPR data of 1, 2, and 4 indicate d(1) x(2) (-y2) ground state of Cu(II) ion with a considerable exchange interaction. The measured cytotoxicity for L and its complexes (1, 2) against three tumor cell lines showed that coordination improves the antitumor activity of the ligand; IC50 for breast cancer cells are approximate to 8.5, 3, and 4 mu g/mL for L and complexes (1) and (2), respectively. (c) 2010 Elsevier B.V. All rights reserved.