Novel Cu-II Complexes of 2-Hydroxy 4-Methoxy Benzylidene 2-Hydroxy Benzhydrazide: Synthesis, Spectral Characterization, Thermal, Antimicrobial, Antioxidant and Catalytic activity Study

The novel hydrazone ligand 2-hydroxy 4-methoxy benzylidene 2-hydroxy benzhydrazide [HL] was prepared by condensing 2-hydroxy benzhydrazide and 2-hydroxy 4-methoxy benzaldehyde in methanol solvent. The Cu-II complexes [Cu(HL)(NO ₃ )].1/3H ₂ O (1a), [{Cu (HL)} ₂ (μ-SO ₄ )].1 ² / ₃ H ₂ O(2a), [Cu(HL)(H ₂ O) Cl](3a) were synthesized by refluxing Cu-II salts CuNO ₃ .3H ₂ O CuSO ₄ .5H ₂ O and CuCl ₂ .2H ₂ O with methanol solution of [HL] and characterized by spectral techniques (FT-IR, ¹ H-NMR, ¹³ C–NMR,UV-Visible, PXRD study).The complexes are further characterized by thermo gravimetric(TG)analysis, molar conductivity, elemental analysis and magnetic susceptibility measurement study. FT-IR spectra provides valuable information about different coordination sites. UV-Visible spectroscopy reflect LMCT bands from 242718- 261780 cm ^-1 and d-d bands in the range of 143884-156250 cm ^-1 in addition to n-π*and π -π*transition in all complexes. Square planar to square pyramidal geometry was proposed for all complexes as illustrated in magnetic, electronic and spectroscopic data. X-ray powder diffraction analysis reveals crystalline nature for all complexes. The experimental results of TGA analysis are in good agreement with spectroscopic data of complexes. A comparison of spectroscopic and physicochemical data are very useful in creating correct assignments and understanding of structure of complex. The ligand act as tribasic tridentate chelating through the phenolate oxygen, azomethine nitrogen and oxygen of enolate donar functionality with copper-II ion. The antibacterial potential of synthesized complex catalysts was evaluated against human pathogenic bacteria such as Bacillus subtilties , Bacillus cereus , Escherichia coli , Pseudomonas velgaris , and Staphylococcus aureus etc. Also, the Cu (II) complexes demonstrate significant antioxidant activity. The catalytic performance in alcohol oxidation using hydrogen peroxide as a green oxidant is also investigated.