Synthesis, characterization, thermal and chelation properties of new polymeric hydrazone based on 2, 4-dihydroxy benzaldehyde

Abstract

A chelating polymer poly(2-hydroxy-4-methacryloyloxy benzaldehyde hydrazone) poly(2H4MBH) was prepared in N,N-dimethylformamide (DMF) at 70°C using benzoyl peroxide as initiator. Poly (2H4MBH) was characterized by infra-red and 1H-NMR spectroscopic techniques. The molecular weight of the polymer was determined by gel permeation chromatography. Polychelates were obtained when the DMF solution of the polymer containing a few drops of ammonia was treated with the aqueous solution of Cu(II)/Ni(II). Elemental analysis of the polychelates indicates that the metal-ligand ratio was about 1: 2. The infrared spectra of polychelates suggest that the metals were coordinated through the oxygen of the phenolic—OH group and nitrogen of the azomethine group. The EPR (Electron paramagnetic resonance) and magnetic moment data indicate a square planar structure for Cu(II) complex whereas octahedral structure for Ni(II) complex. The thermogravimetric analysis, differential calorimetry, and X-ray diffraction data indicated that the incorporation of the metal ions significantly enhanced the degree of crystallinity. The sorption properties of the chelate-forming polymer towards various divalent metal ions Cu(II) and Ni(II) were studied as a function of pH, nature, and concentration of electrolytes.