Analysis of the Cooperativity of Intramolecular Hydrogen Bonds in 1,4-Polyols

The cooperativity of 1,4-polyols and their derivatives is investigated using the recently developed clipping method. Each polyol is transformed into a complex of smaller molecules that have similar interaction energies and similar geometric, spectroscopic, and electron density properties. Energies of the clipped complexes are determined using the supermolecular approach. Symmetry adapted perturbation theory calculations are applied to the clipped complexes within the multibody expansion framework. The main contributions to cooperativity come from two-body interactions between nonbonded groups and from contiguous three-body interactions. The former is largely an electrostatic interaction with a smaller dispersive component, and the latter is principally composed of nearly equal inductive and electrostatic components. The strong correlation between the energy of cooperativity and the strength of the hydrogen bonds of a complex allows the use of model compounds to predict complexation energies for complexes with up to four hydrogen bonding groups. Cooperative effects span a maximum of four contiguous centers.