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 1,6-anhydro-3-deoxy-3-N-methylamine-β-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 here provide a basis to discuss the relevance of cooperativity in molecular recognition of carbohydrates.

Submarine groundwater discharge (SGD) derived nutrient (NO 2-, NO 3-, NH 4 + , PO 4 3-, and

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We investigate the changes in the solvation properties of the natural nucleic acid bases due to the formation of the canonical Watson-Crick hydrogen-bonded complexes. To this end, the changes in the free energy of solvation of the bases induced upon hydrogen-bonded dimerization are analyzed by means of the hydrophobic similarity index, which relies on the atomic contributions to the free energy of solvation determined by the partitioning method implemented in the framework of the MST continuum model. Such an index is also used to examine the hydrophobic similarity between the canonical nucleic acid bases and a series of highly apolar analogues, which have been designed as potential candidates to expand the genetic alphabet. The ability of these analogues to be incorporated into modified DNA duplexes can be related to the large reduction in the hydrophilicity of the natural bases upon formation of the canonical hydrogen-bonded dimers. The results illustrate the suitability of the hydrophobic similarity index to rationalize the role played by solvation in molecular recognition.