Structure, DFT studies, magnetism and biological activity of bis[(μ-azido)-chloro-(1,10-phenanthroline)-copper(II)] complex

The dinuclear complex Bis[(u-azido)-chloro-(1,10-phenanthroline)-copper(II)] (1) was synthesized, and characterized by X-ray. Complex (1) crystallizes in the monoclinic system, it consists of centrosymmetric [CuCl(phen)-mu-N-3](2) dimers bridged by azide groups. The phenanthroline ligand, chloride ion, and eta-N of equatorial bridging azide ligand are coplanar and the square pyramidal copper ion is displaced slightly out of this basal plane, toward the axial bridging azide. The presence of H-bonds, CH-pi and pi-pi interactions form layers of type ABAB within the supramolecular structure of (1). The magnetic susceptibility of (1) versus temperature data showed a weak antiferromagnetic coupling between Cu(II) ions. The best fitting parameters were for g = 2.01 +/- 0.01 and J = 0.55 +/- 0.01 cm(-1). Thermal analysis of (1) exhibited an exothermic peak due to decomposition of azide ligands. The calculated HOMO-LUMO gap from DFT is 0.03098 a.u. (0.08430 eV). Besides, complex (1) exhibited potent chemotherapeutic potential with strong activity after 48 h against MDA-MB-32 (breast adenocarcinoma), HT-29 (colon adenocarcinoma), A549 (lung adenocarcinoma), SF (astrocytoma) and B1 6F10 (melanoma) cell lines, with IC50 value 0.78 mu g/ml (1.21 uM) which is several folds higher than cisplatin 4.88 mu g/ml (16.3 mu M). (1) also has a better therapeutic index and toxicological profile compared to cisplatin, as evidenced by the median lethal dose (LD50).