Transfer Properties of Glycylglycine from Water to Aqueous NaNO₃, NaClO₄, and Na₂SO₄ Solutions

Abstract

Enthalpies of solution and densities of glycylglycine in aqueous solutions of NaNO3, NaClO4, and Na2SO4 were measured at 298.15 K. Standard transfer enthalpies (Δtr H 0), standard transfer partial molar volume (Δtr V ϕ 0), and hydration numbers (N h) have been determined for glycylglycine. All of the Δtr H 0 values are negative in the three salt solutions. The relative order of Δtr H 0 in the same concentration of 1–1 type salts is NaNO3 > NaClO4. The Δtr H 0 in low concentration of Na2SO4 solutions is between the corresponding values in NaNO3 and NaClO4 solutions. With increasing Na2SO4 concentration, the Δtr H 0 values exceed that in NaNO3 solutions. The Δtr V ϕ 0 values are positive and vary in the sequence Na2SO4 > NaNO3 > NaClO4. The results were discussed in terms of various interactions.

Volumetric Properties of Diglycine from Water to Aqueous Amino Acids solutions at 298.15 K and 310.15 K

“…Volumetric methods have been widely used to provided the interaction information between model moleculars and different solvents [1][2][3]. For further understanding the interaction between amino acid residues and peptide backbone, and as a continuation of volumetric investigations on model moleculars systems in our laboratory [4,5], the interactions between diglycine and amino acids have been studied in this paper.…”