Copper(II) Furancarboxylate Complexes with 5-Nitro-1,10-Phenanthroline as Promising Biological Agents

The reaction of copper(II) acetate with 2-furancarboxylic (HFur)/5-nitro-2-furancarboxylic (HNfur) acids and 5-nitro-1,10-phenanthroline (Nphen) in methanol resulted in the formation of the binuclear coordination compounds [Cu2(L)4(Nphen)2]·X (L = Fur (I), Nfur (II); X = H2O (I)), which were structurally studied by direct X-ray diffraction (CCDC no. 2244205 (I) and 2244206 (II)). According to X-ray diffraction data, the coordination environment of the central metal ion in I and II is composed of two nitrogen atoms of Nphen and three oxygen atoms of the acid anions, which thus form the {CuN2O3} tetragonal pyramid in which the copper coordination number is five. Intermolecular hydrogen bonds and stacking interactions between the Nphen aromatic rings provide supramolecular stabilization of I and II. A characteristic feature of supramolecular organization of II is the presence of a coordination bond between the Cu2+ cation and oxygen of the Nphen $${\text{NO}}_{2}^{ - }$$ group of parallel chains. A biological activity assay for complexes I and II concerning the cytotoxic properties against a human ovarian adenocarcinoma cell line (SKOV3) and the mycobacterial strain Mycolicibacterium smegmatis showed an efficient suppression of cell viability. The results of mathematical modeling of the probability of Cu2+ binding to amino acid residues of M. smegmatis proteins suggested the affinity of the Cu(II) ion to a number of amino acids in polypeptide sites. It was shown that metal ion binding in mycobacterial proteins is more characteristic of histidine- and glutamic acid-containing moieties.