Kinetics of Thermal Decomposition and Kinetics of Substitution Reaction of Nano Uranyl Schiff Base Complexes

This study focuses on the synthesis, characterization, and kinetics of substitution reaction of new uranyl Schiff base complexes prepared in a crystalline state as well as in a form of nanoparticles with sizes ranging between 35 and 60 nm. Preliminary Fourier transform infrared spectroscopy (FTIR) and thermogravimetric (TG) measurements indicated no difference between the two forms. The compounds were characterized by UV–vis, ¹H NMR, cyclic voltammetry, X‐ray crystallography, FTIR, TG, and CHN analyses. X‐ray crystallography revealed coordination of the uranyl by the tetradentate Schiff base ligand and one solvent molecule, resulting in seven‐coordinated uranium. Cyclic voltammetry of the complexes in acetonitrile revealed the quasi‐reversible redox reaction. The TG and analysis of Coats–Redfern plots revealed that the kinetics of thermal decomposition of the complexes is of the first order in all stages. The study of the kinetics and the mechanism of the exchange reaction of the coordinated solvent with tributylphosphine was performed by the spectrophotometric method. The second‐order rate constants at four temperatures and the activation parameters revealed an associative mechanism for all corresponding complexes. Anticancer activity of the nano uranyl Schiff base complexes against cancer cell lines (Jurkat) was studied and determined by the MTT (3‐4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyl‐tetrazoliumbromide) assay.