Synthesis, characterization, and multifunctional applications of a novel uranyl(VI) complex: Catalytic activity in synthesis of tetrahydro-4H-chromenes, glucose oxidation, and antimicrobial performance

This study investigates the synthesis, characterization, and multifaceted applications of the uranyl(VI) complex [UO₂(L)(DMF)₂], derived from a tridentate ligand [HL]. The synthesized complex was thoroughly characterized using various techniques, including elemental analysis, ¹H NMR, FT-IR, UV–Vis spectroscopy, conductivity measurements, and single-crystal X-ray diffraction. X-ray crystallography revealed a pentagonal bipyramidal geometry around the uranium(VI) center, with the ligand coordinating to the metal through O, N, and O’ donor atoms. The remaining coordination sites are occupied by two oxo groups and two DMF molecules. Electrochemical studies using cyclic voltammetry revealed quasi-reversible U(VI) to U(V) reduction. Hirshfeld surface analysis highlighted significant intermolecular interactions, including Br···Br halogen bonding, driving the supramolecular structure. The complex exhibited excellent catalytic activity in the synthesis of tetrahydro-4H-chromene derivatives, achieving high yields (94 %) under optimized conditions (8 mol% catalyst, 40 °C) with excellent reusability. Additionally, the complex exhibited excellent catalytic performance in the oxidation of glucose to gluconic acid under mild conditions, achieving a 98 % conversion yield in an alkaline medium. The proposed mechanism involves the formation of a hemiacetal intermediate, followed by catalytic dehydrogenation mediated by the uranyl complex. Furthermore, [UO₂(L)(DMF)₂] demonstrated significantly enhanced antibacterial activity compared to the free [HL] ligand, as evidenced by significantly lower MIC-30 and MIC-50 values, against both Gram-positive (Staphylococcus aureus, Bacillus cereus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria.