Synthesis, spectrochemical characterisation and catalytic activity of transition metal complexes derived from Schiff base modified chitosan

Three novel quadridentate Schiff base complexes, [Cu(OIAC)Cl2], [Co(OIAC)Cl2] and [Ni(OIAC)Cl2] [OIAC, a Schiff base ligand: (([2-oxo-1H-indol-3-ylidene]amino)chitosan)] have been synthesized. The molecular structure of the complexes has been characterised by elemental analyses, magnetic measurements, molar conductance studies, vibrational (FT-IR), electronic (UV–Vis) and 1H NMR spectroscopic techniques. Thermal properties of the complexes have been investigated with TG–DTG analyses. The surface morphological difference of ligand and the complexes has been explored with scanning electron microscopy. The crystallinity of the compounds was analysed by powder X-ray diffraction technique and it was found to be less for the Schiff base (OIAC) and the complexes as compared to the chitosan. The catalytic activities of the complexes have been studied in the oxidation of cyclohexane, using environmental friendly oxidant, hydrogen peroxide. Complex with rough surface has shown higher catalytic activity compared to the other complexes.

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► Chitosan based Schiff base which easily makes heterogeneous complexes is synthesized.
► Cu, Co and Ni complexes are synthesized from the Schiff base.
► Square planar geometry is proposed to the complexes by spectroscopic data.
► Catalytic ability of the complexes is analysed in cyclohexane oxidation.
► Increasing the reaction time, increase the yield percentage of cyclohexanone.