Hydration of cellobiose: Structure and dynamics of cellobiose -(H ₂O) _n, n = 5-25

Solvation of β-cellobiose isomers, cis and trans, in increasingly larger water clusters, is examined here by means of ab initio dynamics. A previously suggested hydration motif, based on a cluster with 2 waters, provides a stable nucleation center for growth of the larger cluster. Key results: (a) the cis form is energetically favored throughout the cluster size range; (b) cis conformer exhibits surfactant properties while (c) trans is better enveloped by water. Water organization at the sugar surface, is significantly different in the two isomers. Rotamer transitions, observed in the isolated sugar at 300 K, are inhibited by the incomplete hydration shell.