Antibacterial and Anticancer Studies of Mononuclear and Binuclear Complexes of Tellurium(IV), Tantalum(V), Selenium(IV), and Niobium(V) Urate by Spectroscopic Methods

Novel tellurium(IV), tantalum(V), selenium(IV), and niobium(V) urate complexes were prepared with molar ratios 1:1 and 2:1 (metal:ligand). The uric acid (H 4 UA) ligand was reacted with TeCl 4 , TaCl 5 , SeCl 4 , and NbCl 5 metal chlorides in the presence of NaOH to yield mononuclear and binuclear complexes. The mononuclear tellurium (IV) and tantalum(V) complexes formulas [Te(H 3 UA)(H 2 O) 3 (Cl)]∙2Cl·2H 2 O ( I ) and [Ta(H 3 UA)(H 2 O) 2 (Cl) 2 ]·2Cl∙4H 2 O ( II ), as well as binuclear selenium(IV) and niobium(V) complexes [Se 2 (H 2 UA)(Cl) 4 ]·2Cl∙4H 2 O ( III ) and [Nb 2 (H 2 UA) (Cl)8] ∙3H 2 O ( IV ), were obtained in the presence of NaOH at pH 8–9. The metal complexes were characterized by elemental analyses, FTIR, 1 H-NMR, electronic, conductivity, and thermal analyses. In the case of mononuclear complexes, the coordinating sites are the pyrimidine carbonyl oxygen atom of C(6)=O group and imidazole nitrogen of deprotonated N(7)–H. In addition to these coordinating sites, the pyrimidine carbonyl oxygen atom of C(2)=O and pyrimidine nitrogen of deprotonated N(3)–H are involved in coordination in binuclear complexes. The metal urate complexes exhibited six-coordinate geometries, while the binuclear selenium is four-coordinate. The antibacterial and anticancer activities of the urate complexes were investigated. No antibacterial activity was observed in any treatments, except for gram-negative Klebsiella, which showed a slight effect. The metal complexes showed high proportions of cell viability percentage after treatment in both colorectal adenocarcinoma (Caco-2) and breast cancer (MCF-7) cell lines using the neutral red uptake assay.