Role of intramolecular hydrogen bonds in the intermolecular hydrogen bonding of carbohydrates

The cooperativity effects in hydrogen-bonded intermolecular interactions of carbohydrates are examined in this study. The nature of such effects is explored with ab initio quantum mechanical and density functional methods. Calculations are performed for complexes of 1,3-propanediol and n-propanol, which are used as model compounds to analyze hydrogen bond cooperativity in the dimerization of the sugar 1,3-diaxial diol I,6-anhydro-3-deoxy-3-N-methylamine-beta-D-glucopyranose. In addition to the influence of cooperativity in the binding energy, the magnitude of cooperativity effects is also examined from the change in key properties related to the formation of hydrogen bonds between monomers, which include bond lengths, atomic partial charges, electron density at bond critical points, and stretching frequencies. The results reported hew provide a basis to discuss the relevance of cooperativity in molecular recognition of carbohydrates.