Copper(I) complexes with quinolone appended 1,8-naphthalimide conjugates: structural characterization, DNA and protein binding and cytotoxicity studies

A novel 1,8-naphthalimide containing ligand (L) and its three mononuclear complexes with different anions, [Cu(L)(2)](NO3)center dot 3(H2O) (1), [Cu(L)(2)]Cl center dot 4(H2O) (2), [Cu(L)(2)]ClO center dot DMF (3) was synthesized and characterized by NMR, infrared spectroscopy, elemental analysis, ESI-MS and single crystal X-ray crystallography. Single-crystal diffraction analysis of ligand L revealed the non-planar structure of the ligand with intermolecular pi center dot center dot center dot pi stacking interaction between naphthaIimide moieties. Single-crystal X-ray studies of the complexes evidenced a seesaw geometry around the Cu(I) center. A competitive DNA binding and absorption titration study suggests an intercaIative mode of DNA binding by complex 1. The fluorescence study of bovine serum albumin (BSA) with complex 1 revealed a dynamic quenching mechanism. A549 (adenocarcinoma human alveolar basal epithelial cells), MCF-7 (breast cancer cell Line)) cell Lines were used to assess the cytotoxicity of complex 1 using the MTT (3-[4,5-dimethyIthiazoIe-2-yl]-2,5-diphenyItetrazohum bromide) assay. Complex 1 displayed improved cytotoxicity towards cancer cell Lines in comparison with cis-platin. The cell accumulation study was investigated by fluorescence microscopy.