Spectroscopic and Potentiometric Studies of N-(2- Hydroxybenzyl)-L-α-Valine Cobalt (II) Complex

Abstract

A Schiff base was prepared from the reaction of 2-hydroxybenzylaldehyde and L-valine. The reaction of the Schiff base and cobalt (II) chloride formed 2-hydroxybenzylaldehyde and L-valine cobalt (II) complex. The Schiff base is crystalline white and has a yield of 66%. The prepared complex is pale brown, has a yield of 68% and decomposition temperature of 274oC. The Schiff base and its cobalt (II) complex are insoluble in most common solvents however they are soluble in ethanol-water mixture. The molar conductance of the cobalt (II) Schiff base complex compound determined is 5.2 ohm cm2 mol-1. The infra-red spectra of the Schiff base showed band in the range 1480 -1520cm-1, assignable to v(C=N) stretching vibrations, the same band is observable in the cobalt (II) Schiff base complex. The broad band in the range 3270 - 3420cm-1 observed in Schiff base is assigned to v(O-H) stretching vibrations. The dissociation constant (pKa) of N – (2 – hydroxybenzyl) - L -a - valine Schiff base determined is 8.84. The average number of the Schiff base to cobalt (II) ion is 1 (one).