Synthesis and Inhibitory Activity of Schiff Base Surfactants Derived from Tannic Acid and Their Cobalt (II), Manganese (II) and Iron (III) Complexes Against Bacteria and Fungi

A series of tannic acid Schiff base surfactants and their iron, cobalt and manganese metal complexes were synthesized and their structures were elucidated by microelemental analysis, FTIR and 1 H-NMR data. The surface activities of the surfactants were increased by increasing the number of substituents, as represented from the surface tension measurements. The metal complexes showed higher critical micelle concentrations and surface tension reduction at critical micelle concentration. The antimicrobial activity in terms of inhibition zone diameter and minimum inhibitory concentrations showed increasing activity of the metal complexes over their parent compounds against Gram-positive, Gram-negative bacteria and fungi.