Biologically active novel N, N, O donor tridentate water soluble hydrazide based O-carboxymethyl chitosan Schiff base Cu (II) metal complexes: Synthesis and characterisation

Water soluble hydrazide based O-carboxymethyl chitosan Schiff base ligands have been prepared from chitosan and a mixture of benzoic acidhydrazide with beta-diketone by carboxymethylation using mono chloroaceticacid (MCA) through in-situ reaction. The degree of deacetylation of chitosan was determined by elemental analysis and potentiometric titration. Schiff base ligands and the functional groups were characterised by FT-IR, H-1, and C-13 NMR spectroscopic techniques. The crystallinity of ligands and complexes was evaluated by X-ray powder diffraction (XRD) studies. Thermal stability of all the synthesized compounds was investigated by thermo gravimetric analysis and differential thermal analysis (TGA-DTA) which revealed the presence of metal oxide (CuO) residue to elevate the temperature to >500 degrees C. Filed emission scanning electron microscopic (FESEM) analysis revealed that Cu (II) complexes were more amorphous in nature than chitosan and Schiff base ligands. Vibrating sample magnetometer (VSM) studies reported that the d(9) configuration of the metal complex was paramagnetic in nature and the geometry of the complex was square pyramidal. The antimicrobial activity of the synthesized hydrazide Cu (II) complexes was characterised by agar plate method, anti-inflammatory study was characterised by egg albumin denaturation technique and total antioxidant activity was characterised by phosphomolybdenum method. (C) 2019 Elsevier B.V. All rights reserved.