Modulation in physico-chemical characteristics of some polyhydroxy solutes in presence of L-glycine: Volumetric and NMR spectroscopic approach

Volumetric and H-1 and C-13 NMR spectroscopic studies have been exploited to study molecular interactions of some polyhyroxy solutes with L-glycine in aqueous solutions. Apparent molar volumes, V-2,V-phi for monosaccharides; (+)-n-mannose, (+)-n-glucose, and (-)-L-sorbose, disaccharides; (+)-maltose monohydrate, and (+)-cellobiose, deoxy-derivatives of hexoses; 6-deoxy-n-mannose, 2-deoxy-n-glucose, methyl glycopyranosides; (+)-methyl alpha-n-mannopyranoside, and (+)-methyl alpha-n-glucopyranoside, and polyols; n-mannitol, n-sorbitol, and myo-inositol in 0.05, 0.15, 0.25, 0.35 and 0.50 mol kg(-1) aqueous solutions of L-glycine have been determined from density, rho data measured at 288.15, 298.15, 308.15 and 318.151( under atmospheric pressure, p = 0.1 MPa. The data were processed to obtain the standard partial molar volumes, V-2 degrees at infinite-dilution and the corresponding volumes of transfer, Delta trV(2)degrees of solutes from water to aqueous solution of L-glycine. Other parameters such as partial molar expansion coefficients (partial derivative V-2 degrees/partial derivative T)(P) and their second-order derivatives (partial derivative V-2(2)degrees/partial derivative T-2)(P), and pair and higher-order volumetric interaction coefficients (V-AB and V-ABB) have also been obtained. These parameters have been utilized to discuss various types of interactions on the basis of co-sphere overlap model. H-1 and C-13 NMR spectroscopic studies for polyhydroxy solutes were carried out in 0.10 mol kg(-1) L-glycine prepared in 9:1 (w/w) H2O-D2O solvent. NMR results show more downfield shift in ternary system than in pure L-glycine solution, hence suggesting that hydrophilic-ionic interactions predominate over hydrophilic/hydrophobic-hydrophobic interactions occurring between solute and L-glycine molecules. (C) 2015 Elsevier B.V. All rights reserved.