Synthesis, Characterization and Anti-Microbial Assessment of N, N’ - Bis(4-benzeneazo salicylidene)-o-Phenylenediiminatomanganese(II) Complex

Abstract

A Schiff base, N,N’ –bis (4- Benzeneazo salicylidene)-o-phenylenediimine was prepared by 2:1 molar condensation of 4 – (Benzeneazo) salicylaldehyde with o-phenylenediamine. The manganese(II) complex of the schiff base was prepared and characterized by determination of its solubility, melting point and molar conductivity, as well as by elemental analysis, infrared spectroscopy, bioassay and potentiometry. The complex prepared is greenish yellow, decomposes at 263^oC, soluble in dimethylsulphoxide (DMSO) and dimethylformamide (DMF) but insoluble in most organic solvents. The molar conductivity of the complex determined is 5.50 ohm^-1cm²mol^-l, revealing a non-electrolyte compound. The infrared spectral data of the Schiff base showed a band at 1590cm^-1, which is attributable to v(C=O) stretching frequency. The same band was observed in the manganese(II) complex but at a lower frequency of 1565cm^-1, suggesting coordination of the Schiff base ligand. The bands in the region 586cm^-1 and 500cm^-1 in the complex are assigned to v(Mn-N) and v(Mn-O) stretching vibrations, respectively, confirming coordination of the Schiff base to the manganese(II) ion. The dissociation constant of the Schiff base is 11.67, indicating a weak acid. The mean number of Schiff base coordinated to manganese (II) ion is one, and the stability constant and Gibb’s free energy of the complex are 2.51x10¹² and -69.16KJmol^-1, respectively. The antifungal and antibacterial tests carried out on the Schiff base and its manganese(II) complex showed moderate activity. The complex formed by the interaction of the prepared Schiff base and manganese (II) salt is stable and bioactive.

Keywords: 4 - (Benzeneazo) Salicylaldehyde, complex compound, molar conductance, Potentiometry, schiff base, solubility.