Effect of urea on speciation of cobalt(II) complexes of L-glutamine and succinic acid

Abstract

Speciation of CoII complexes of L-glutamine (Gln) and succinic acid (Suc) in 0.0 -36.83%, wyv ureawater mixtures at an ionic strength of 0.16 mol dm À3 and temperature 303.0 AE 0.1 K has been investigated pH-metrically. The species detected for Gln complexes are ML, MLH and ML 3 H and those for Suc are ML, MLH and ML 2 H. The stability of the complexes decreased with increased urea content due to the electrostatic forces, denaturing power and complexing ability of urea. The relative stabilities of the species in urea -water and ethylene glycol -water mixtures are compared based on the dielectric constants. The species distribution and the plausible equilibria for the formation of the species are also presented.