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

The dinuclear complex Bis[(µ-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)µ-N3]2 dimers bridged by azide groups. The phenanthroline ligand, chloride ion, and ƞ-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-π and π-π 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 B16F10 (melanoma) cell lines, with IC50 value 0.78 μg/ml (1.21 µM) which is several folds higher than cisplatin 4.88 μg/ml (16.3 µM). (1) also has a better therapeutic index and toxicological profile compared to cisplatin, as evidenced by the median lethal dose (LD50).