Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Limiting standard enthalpies of dilution (dilH) and Jones-Dole viscosity B-coefficients of various polyhydroxy solutes viz., saccharides, their methyl and deoxy derivatives and sugar alcohol in (0.05, 0.15, 0.25 and 0.35) mol*kg-1 thiamine HCl(aq) and pyridoxine HCl(aq) solutions have been determined from heat change (q) and viscosity () data at T = (288.15 to 318.15) K and pressure, p = 0.1 MPa. The corresponding transfer parameters (trdilH, trB), change in heat capacity (dilCp,2,m), the enthalpic (hAB and hABB) and viscometric (AB and ABB) pair and triplet interaction coefficients have also been derived. The dB/dT coefficients have been calculated and discussed in terms of kosmotropic or chaotropic nature of solutes in aqueous solutions of vitamins. The present results have also been compared with previously reported studies carried out in -ascorbic acid.17 Further, NMR spectroscopy has been employed to understand the nature of interactions occurring in ternary solution {polyhydroxy solute + vitamins + 9:1 (w/w) H2O-D2O} at molality, mB = 0.15 mol*kg-1 and T = 300.15 K. The results have been explained in terms of contributions due to hydrophilic-hydrophilic/hydrophobic interactions and H-bonding between solute-solute/cosolute molecules. The effect of stereochemistry and molecular conformations of both polyhydroxy solutes and cosolutes (vitamins) have also been discussed. 1. INTRODUCTION The understanding about solvation behavior of saccharides and their derivatives in aqueous solutions is very essential due to their recognition in various biological processes like protein/enzyme stability, cellular interactions, protective efficacy, etc. Saccharides are appropriate models to study the hydration characteristics of proteins and nucleic acids as these stabilize the protein conformations and impede denaturation due to reagents.1-6 Sugar alcohols