Thermodynamic studies on complexation of dioxyvanadium(V) with serine

Abstract

The solution equilibria of the dioxyvanadium(V) complex formed by serine in acidic media (pH < 2.3) has been investigated potentiometrically and spectrophotometrically. Under these conditions the 1:1 complex has the formula VO2Y, where Y~r epresents the fully dissociated aminocarboxylate anion. The stability constant of VO2Y was determined log K\ 2 = 10.098 ± 0.146 at 25 ± 0.1 °C and 7=1 mol-dm~3 sodium perchlorate. The protonation constant of serine was also determined potentiometrically under the above conditions.

Complex Formation between Aspartic Acid and Molybdenum(VI)

“…piZi and pKi refer to the first and second dissociation constants of the first and second carboxyl groups, respectively, and pK3 denotes the deprotonation of the amino group. The above pK values were determined by potentiometric titration under the same condition of temperature and ionic strength as described before (Gharib et al, 1993).…”

Complexation of Leucine by Dioxovanadium(V) in Mixed Solvent Systems

“…Complexation of Vanadium(V) with Leucine. The method based on the relationship A ) f(pH) was employed (Gharib et al, 1993), on account of the high stability of the complex studied. Absorbance, A, and pH were measured for solutions containing V(V) (10 -4 mol‚dm -3 ) with a large excess of ligand (10 -2 mol‚dm -3 ) of pH ranging from (1.20 to 10.20) in various solvent systems, and the results are shown in Figure 1 and are listed in Table 2.…”

Thermodynamic Studies on Complexation of Glutamic Acid with Dioxovanadium(V) in Mixed Solvent Systems

“…The method based on the relationship A ) f(pH) was employed on account of the high stability of the complexes studied. 9,19 Absorbance, A, and pH were measured for solutions containing V(V) (10 -4 mol dm -3 ) with a large excess of Glu (10 -2 mol dm -3 ) of pH ranging from (1.3-5) in various solvent systems. Under these experimental conditions, hydrolysis of vanadium(V) ion, VO 2 + , was negligible.…”