Synthesis, crystal structure, cytotoxic activity and DNA-binding properties of the copper (II) and zinc (II) complexes with 1-[3-(2-pyridyl)pyrazol-1-ylmethyl]naphthalene

Abstract

A new ligand L, 1-[3-(2-pyridyl)pyrazol-1-ylmethyl]naphthalene, and its two metal complexes, [Cu( L) 3](ClO 4) 2 ( 1) and [Zn( L) 3](ClO 4) 2(H 2O) 2 ( 2), have been synthesized and characterized. The crystal structure of complex 1 was determined by single crystal X-ray diffraction, which crystallized in monoclinic, space group P2 1/ n with unit cell parameters, a = 12.710(4) Å, b = 12.135(3) Å, c = 33.450(9) Å, β = 93.281(5)° and Z = 4. The Cu atom was six-coordinated to N(1), N(2), N(4), N(5), N(7) and N(8) from three L ligands and formed a slightly distorted octahedral geometry. Complexes 1 and 2, and ligand L were subjected to biological tests in vitro using three different cancer cell lines (HL-60, BGC-823 and MDA-MB-435). Complex 1 showed significant cytotoxic activity against three cancer cell lines. The interactions of complexes 1 and 2, and ligand L with calf thymus DNA were then investigated by thermal denaturation, viscosity measurements and spectrophotometric methods. The experimental results indicated that complexes 1 and 2 bound to DNA by intercalative mode via the ligand L. The intrinsic binding constants of complexes 1 and 2, and ligand L with DNA were 1.8 × 10 4, 5.4 × 10 3 and 2.76 × 10 3 M −1, respectively.