Synthesis, Characterization and Biological Activity of New 3-substitued-4-amino-5-hydrazino-1,2,4-triazole Schiff Bases and Their Cu(II) Complexes: A New Approach to CuO Nanoparticles for Photocatalytic Degradation of Methylene Blue Dye

Three new Schiff base compounds were synthesized via condensation of 3-R-4-amino-5-hydrazino-1,2,4-triazole with dibenzoylmethane [R = H, CH 3 , and CH 2 CH 3 namely L1, L2, and L3, respectively]. The synthesized Schiff bases were characterized using melting point, CHN elemental analyses, FT-IR, and 1 H-NMR. The corresponding Cu(II) Schiff base complexes were synthesized via refluxing the prepared Schiff bases with CuCl 2 ·2H 2 O. The synthesized complexes have been characterized by means of different spectral tools (FT-IR, ESR, and UV–Vis spectra) in addition to elemental analysis, magnetic moment, conductivity, and thermal analysis. The synthesized copper complexes are nonelectrolytes in N,N -dimethylformamide (DMF) based on their conductance values. Using modified Bauer-Kirby method, the Schiff bases and their Cu(II) complexes have been tested for antifungal ( Candida albicans and Aspergillus flavus ) and antibacterial ( Staphylococcus aureus and Escherichia coli ) activities. Moreover, CuO nanoparticles were produced via thermal decomposition of the synthesized Cu(II) complexes at 650 °C. The produced nanoparticles were characterized using XRD, HR-TEM, FT-IR, and UV–Vis spectroscopy. The CuO nanostructures exhibited good photocatalytic activity for the degradation of methylene blue dye in the presence of hydrogen peroxide with 77.36% degradation efficiency in 360 min. Graphical Abstract Proposed structure of the synthesized Cu(II) complexes