Catalytic and biological reactivities of mononuclear copper (II) and vanadyl (II) complexes of naphthalenylimino-phenolate sodium sulfonate

Two novel water-soluble mononuclear Cu(II) and VO(II)-complexes (CuSL and VOSL, respectively) were synthesized from easily accessible 2-((naphthalen-1-ylimino)methyl)phenolate sodium sulfonate as a Schiff base ligand (HSL). HSL, CuSL and VOSL were characterized by various spectral tools. Their catalytic potential was investigated and compared in 1,2-cyclohexene epoxidation using H2O2 or tBuOOH as an oxidizing agent, and in C―C cross-coupling protocols, including Suzuki-Miyaura and Sonogashira reactions, under homogeneous reaction conditions. Both complexes exhibited good catalytic potential in the epoxidation reaction. VOSL complex with the high oxidation state metal ion (VIV) exhibited slightly better performance in the epoxidation reaction, provided 93, 77 and 89% yield in acetonitrile, water and under solvent free condition. In contrast CuSL complex provided 89, 71 and 79% yield under the same reaction condition. While in Suzuki-Miyaura and Sonogashira C―C reactions using phenylboronic acid or phenylacetylene with aryl halides, CuSL afforded better catalytic potential (89% for Suzuki-Miyaura and 77% yield for Sonogashira C―C products) than VOSL catalyst (73% and 51% yield respectively). DFT studies were also carried to understand the catalytic behavior of CuSL and VOSL catalysts in their catalytic processes. Additionally HSL, CuSL and VOSL were also explored for their biological potential against some pathogens strains, as antimicrobial, antioxidant and anticancer agents. Both complexes (CuSL and VOSL) showed better inhibiting potential than their free ligand. The complex ctDNA-interaction was examined by UV–vis. spectrophotometry, viscosity measurements and gel electrophoresis to determine the nature of binding. Additionally, molecular docking was also carried out for better understanding.