Utilization of carboxymethyl cellulose based on bean hulls as chelating agent. Synthesis, characterization and biological activity

Abstract

Binary and ternary complexes of Ni 2+, Cu 2+, Ag + and UO 2 2+ with the prepared carboxymethyl cellulose in its sodium salt (P-NaCMC) and pyridine (py) as secondary ligand have been prepared. Probable structures of the binary and ternary complexes were inferred via elemental analysis, spectral data (IR, mass and solid reflectance) as well as magnetic susceptibility measurements, thermal and XRPD analysis. The change in the selected vibrational absorption bands in IR spectrum of P-NaCMC upon coordination with metal ions investigates the coordination mode of P-NaCMC to be the two vicinal uncarboxylated diol groups (2- and 3-hydroxyl groups) of the glucopyranose rings in addition to the carbonyl oxygen atom of the carboxylate group while the coordination mode of pyridine ligand is the ring nitrogen. The mass spectra confirmed the proposed structure of the synthesized compounds. The solid reflectance spectral data and magnetic moment measurements suggest the geometrical structures for the metal complexes. Thermal studies suggest a mechanism for degradation of P-NaCMC and its metal complexes as function of temperature supporting the chelation modes. Also, the activation thermodynamic parameters, such as, Δ E *, Δ H *, Δ S * and Δ G * for the different thermal decomposition steps of P-NaCMC and its metal complexes were calculated. Antimicrobial activities of P-NaCMC and its binary and ternary complexes were studied against S. aureus and S. pyogenes (Gram-positive bacteria), P. phaseolicola and P. fluorescens (Gram-negative bacteria) and the fungi; F. oxysporum and A. fumigates using agar disc diffusion method. The results showed that all the metal complexes, especially Cu 2+ ternary complex have higher antibacterial and antifungal activities than P-NaCMC.