Vibrational analysis of molecular interactions in aqueous glucose solutions. Temperature and concentration effects.

A vibrational analysis using FTIR and Raman spectroscopies was carried out on aqueous glucose solutions with a wide range of solute molar fractions and temperatures. The analysis was aimed at revealing structural changes in the local hydrogen-bonding (HB) network of liquid water, correlating these with the conservative properties of biomolecules, and comparing them with those of other sugars. The results of our measurements clearly show that the action of glucose is 2-fold; on one hand, there is a linkage with free hydroxyls of water; on the other, there is a slight lessening of the ordered (tetrahedral) H-bonded assembly of bulk H(2)O. These opposite effects do not balance each other, so the average HB interaction strength decreases on increasing glucose concentration. As a result, there is a reduction in the temperature dependence of solutions structure. In our opinion, this could be related to the low bioprotective action of this carbohydrate.