Synthesis, Structural Characterization, and Antimicrobial Activity Evaluation of New Binuclear Niobium(V) Tartrate Complexes with Biologically Important Drugs

The new binuclear niobium(V) complexes of the type [[NbO(L)C4H4O6]2C4H4O6] (where L？=？DMH, IMH, IPH, FPH, TMT) were prepared with biologically important drugs and characterized by using elemental analysis; IR, 1H-NMR, and UV-Vis spectral studies, and thermogravimetric analysis. The molar conductance measurement of all the complexes in DMF solution corresponds to 1？:？1 electrolytic nature. All complexes were of the pure diamagnetic character and were found to have six-coordinate octahedral geometry. The antimicrobial activity of these complexes has been screened against two Gram-positive and two Gram-negative bacteria. Antifungal activity against two different fungi has been evaluated and compared with controls. All the complexes inhibit the growth of both Gram-positive and Gram-negative bacteria to a competent level. 1. Introduction Metal ions play a vital role in a vast number of biological processes. Niobium ions form complex species with virtually all types of neutral and anionic donors. Niobium and its compounds have a broad spectrum of applications. They are used for the fabrication of special materials for microelectronics and optics, superconductors, refractory materials, catalysts, and alloys [1–5]. As an important alloy element in steels, niobium can greatly affect the properties of a sample, such as the intensity at high temperature, the ability of tarnish resistance, and temper brittleness [6, 7]. Niobium steels are valuable constructive materials for the chemical and nuclear industries, jet and rocket engines, gas pipelines, and turbines [8]. The chemistry of the early transition metal peroxo complexes has received special attention due to their importance in a variety of biological, pharmaceutical, and industrial processes [9]. Uses of metal ions in therapeutic agents are known to accelerate drug action, and their efficacy is enhanced upon the coordination with a metal ion [10]. The antimicrobial properties of metal complexes have been recognized for centuries and have represented some of the most fundamental breakthroughs in medicinal history [11]. However, Nb(V) complexes have been limitedly studied as the biocidal agents [12, 13]. Thus, we intended to study the ability of niobium complexes as good antimicrobial agents. The present work describes the preparation of new niobium(V) tartrate complexes containing active pharmaceutical drugs (Figure 1). The isolated complexes were studied via elemental analysis; IR, 1H-NMR, and UV spectroscopies; and TGA. In view of the biological activity of the complexes and diverse coordinating ability of