Complexes of uranyl(II), vanadyl(II) and zirconyl(II) with orotic acid “vitamin B13”: Synthesis, spectroscopic, thermal studies and antibacterial activity

A convenient method for the preparation of complexes of the uranyl [UO2]2+, vanadyl [VO]2+ and [ZrO]2+ ions with vitamin B13 (Orotic acid; H3OA) is reported and this has enabled three complexes of orotate anion (1−) to be formulated: [M(C5H3N2O4)2(H2O)2]·(H2O)n [where M = [UO2]2+, [VO]2+, [ZrO]2+; n = 1, 6, 3, respectively]. The new bisorotate (H2OA)1− complexes were synthesis and characterized by elemental analysis, molar conductivity, spectral methods (UV–vis, mass, 1H NMR and mid infrared spectra), and simultaneous thermal analysis (TG and DTG) techniques. Physical measurements indicate that the neutral orotic acid ligand in its mono/anion form, is bonded to oxometal ions through the carboxylic groups (two monodentate orotate anions and complete the coordination sphere by coordinated water molecules). The molar conductance data confirm that the orotate complexes are non-electrolytes. The X-ray powder diffraction (XRD) as well as scanning electron microscopy (SEM) shows that the studied complexes have amorphous structures. The kinetic thermodynamic parameters, such as, E∗, ΔH∗, ΔS∗ and ΔG∗ are calculated from the DTG curves. The antibacterial activity of the orotic acid and their complexes was evaluated against gram positive/negative bacteria.