Three new Cu(II) and Cd(II) complexes with 3-(2-pyridyl)pyrazole-based ligand: Syntheses, crystal structures, and evaluations for bioactivities

Three new complexes [Cu(L)(2)(NO3)](NO3)(H2O)(1/2)(CH3OH)(1/2) (1), [Cd(L)(2)(NO3)(2)](H2O)(3) (2) and [Cd(L)(2)(ClO4)(CH3OH)](ClO4)(H2O)(1/4)(CH3OH) (3) (L = 1-[3-(2-pyridyl)pyrazol-l-ylmethyl]naphthalene) were synthesized and characterized by elemental analyses, IR and X-ray diffraction analysis. Among them, the Cu(II) and Cd(II) ions were both coordinated by four N donors from two distinct L ligands via N,N-bidentate chelating coordination mode. Additional weak interactions, such as the face-to-face pi-pi stacking and C-H... 0 H-bonding interactions, linked the mononuclear unit into ID chain and further into 2D network. Complexes 1-3 were subjected to biological assays in vitro against six different cancer cell lines. All of them exhibited cytotoxic specificity and notable cancer cell inhibitory rate. The interactions of 1-3 with calf thymus DNA were investigated by thermal denaturation, viscosity measurements, spectrophotometric and electrophoresis methods. The results indicate that these complexes bound to DNA by intercalation mode via the ligand L and had different nuclease activities, which were in good agreement with their DNA-binding strength. Moreover, the central metal ions of 1-3 played a vital role in DNA-binding behaviors, DNA-cleavage activities and cytotoxicities, whereas the contribution of the different counter anions to their bioactivities also should not be ignored. (c) 2006 Elsevier Inc. All rights reserved.