Three New Complexes of Theophylline Drug with Sc(III), Nb(V), and W(VI) Ions: Spectroscopic, Thermal Stability, and Antimicrobial Studies

Abstract

Herein, three newly synthesized theophylline (TPE) complexes with transition metal ions (Sc³⁺, Nb⁵⁺ and W⁶⁺) are characterized by FT-IR and UV-Vis spectra, magnetic and thermogravimetric analysis, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmittance electron microscopy (TEM). FT-IR spectra confirm that the metal ions coordinate to TPE chelate as a mono-dentate ligand via nitrogen atom N⁷ of the deprotonated NH group. Theophylline complexes are formed in 1 : 2 (metal: ligand) stoichiometry. According to TGA curves the complexes do not contain crystallization water outside the binding spheres. The accumulated data indicate the octahedral geometry for Sc(III) and W(VI) complexes. The Nb(V) complex is four coordinated. Sc(III) And W(VI) complexes in DMSO demonstrate non-electrolytic nature, and Nb(V) complex acts as an electrolyte. The TPE complexes are tested in vitro against bacteria (Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus) and fungi (Aspergillus flavus and Candida albicans). The complexes exhibit high antimicrobial activity. The in vitro anticancer activity of Sc(III) complex is screened against the human hepato cellular carcinoma (HepG-2) tumor cell line.