The Effects Of Substituent, Chairal Recognition And Salt On Enthalpic Pairwise Interactions Of Monosaccharides And Their Derivatives

As a kind of organic matter with higher content and wide distribution in life beings, sugar plays an important role in diverse life activities. Because sugar in life functions all in biological fluids, the study of thermodynamic properties of sugar in aqueous electrolyte solutions is of great importance for understanding life processes. The chemical diversity and stronger hydration tendency of sugar molecules make it very difficult for one to describe exactly various weak interactions between sugar and other molecules in solution, however, such weak interactions often play a key role in the physiological activities of life. In this thesis, we have determined dilution enthalpies and enthalpic pairwise interactions of some monosaccharides and their derivatives in aqueous solutions of common inorganic salts by microcalorimetriy, and have discussed the substituent, chiral recognition and salt effects on their enthalpic pairwise interactions. The related studies provide a mass of valuable experimental data of thermodynamic properties for deep insight into interactions of sugar molecules, and therefore are of significant for enriching and developing solution chemistry of sugar. The main contents of this study can be divided into the following four parts.In the first part, dilution enthalpies of D-(-)-lyxose and L-(+)-lyxose in aqueous Na Cl and KCl solutions of various molalities(b = 0-3.01kgmol??) have been determined respectively at T = 298.15 K by an isothermal titration calorimeter(MicroCal ITC200). The corresponding homotactic enthalpic pairwise interaction coefficients(hxx) of the two lyxose enantiomers have been calculated according to the McMillan-Mayer’ theory. The effects of chiral recognition and salts on the tendencies of hxx have been analyzed and discussed from the point of view of solute-solute interaction(preferential configuration model) and solute-solvent interaction(hydrophilic-hydrophobic competition equilibrium model).In the second part, dilution enthalpies of D-(+)-mannose and L-(-)-mannose in aqueous NaCl and KCl solutions of various molalities(b = 0-3.01kgmol??) have been determined respectively at T = 298.15 K by MicroCal ITC200. The corresponding homotactic enthalpic pairwise interaction coefficients(hxx) have been calculated according to the McMillan-Mayer’ theory. The effects of chiral recognition and salts on the tendencies of hxx have been analyzed and discussed from the point of view of solute-solute interaction(preferential configuration model) and solute-solvent interaction(hydrophilic-hydrophobic competition equilibrium model).In the third part, dilution enthalpies of four derivatives of monosaccharides, including 2-deoxy-D-glucose, N-acetyl-D-glucosamine, 2-deoxy-D-galactose and N-acetyl-D-galactosamine, in aqueous NaCl solutions of various molalities(b = 0-3.01kgmol??) have been determined respectively at T = 298.15 K by MicroCal ITC200. The corresponding hxx values of them have been calculated according to the McMillan-Mayer’ theory. The effects of chiral recognition and salts on the tendencies of hxx have been analyzed and discussed from the point of view of solute-solute interaction and solute-solvent interaction.In the fourth part, dilution enthalpies of L-carnitine in aqueous NaCl,KCl and NaBr solutions of various molalities(b = 0-3.01kgmol??) have been determined respectively at T = 298.15 K by MicroCal ITC200. The corresponding hxx values have been calculated according to the McMillan-Mayer’ theory. The effects of salts on the tendencies of hxx have been analyzed and discussed from the point of view of solute-solute interaction and solute-solvent interaction.