Multifunctional Cu–phen/bpy modified molybdovanadate-based polyoxometalates for catalytic hydrogen generation and antibacterial applications

Two structurally related Anderson-type polyoxometalate (POM)-supported copper complexes were synthesized and evaluated for hydrogen generation and antibacterial activity. In this context, two molybdovanadate-based compounds, [Cu(phen) 2 ] 3 [Mo 6 V 2 O 26 ]·4H 2 O (H41) and [Cu(bpy) 2 ] 3 [Mo 6 V 2 O 26 ]·4H 2 O (H42), were prepared via coordination of the [Mo 6 V 2 O 26 ] 6- cluster with Cu(CH 3 COO) 2 in the presence of 1,10-phenanthroline or 2,2′-bipyridine ligands in aqueous solution. The obtained complexes were characterized by FT-IR, ¹H NMR, ICP-MS, TGA, and elemental analysis. Their catalytic performance toward hydrogen generation from NaBH₄ methanolysis was evaluated by systematically investigating the effects of catalyst amount, NaBH₄ concentration, and temperature on the reaction kinetics. Both complexes exhibited catalytic activity, with H42 showing more favorable kinetic behavior. The apparent activation energies were determined to be 38.68 kJ mol⁻¹ for H41 and 16.20 kJ mol⁻¹ for H42. For H42, the activation enthalpy and activation entropy were determined to be 13.64 kJ mol⁻¹ and − 97.52 J mol⁻¹ K⁻¹, respectively. H42 also exhibited a TOF value of 2706.14 h⁻¹. In addition to their catalytic activity, both compounds exhibited concentration-dependent antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus , with H41 generally showing higher inhibition under the investigated conditions. The contrasting catalytic and antibacterial responses of H41 and H42 indicate that modification of the Cu–N-donor coordination environment can differently influence the functional properties of the molybdovanadate-based hybrid platform. Overall, these findings highlight the potential of Cu–N-donor ligand/molybdovanadate hybrids as multifunctional materials and demonstrate the importance of ligand modification in tuning their catalytic and antibacterial behavior.