Molecular modeling in dioxane methanol interaction

Molecular interaction between dioxane and methanol involves certain polar and nonpolar bonding to form a one to one complex. Interatomic distances between hydrogen and oxygen within 3 angstrom have been considered as hydrogen bonding. Optimizations of the structures of dioxane-methanol complexes were carried out considering any spatial orientation of a methanol molecule around a chair/boat/twisted-boat conformation of dioxane. From 45 different orientations of dioxane and water, 23 different structures with different local minima were obtained and the structural characteristics like interatomic distances, bond angles, dihedral angles, dipole moment of each complex were discussed. The most stable structure, i. e., with minimum heat of formation is found to have a chair form dioxane, one O-H center dot center dot center dot O, and two C-H center dot center dot center dot O hydrogen bonds. In general, the O-H center dot center dot center dot O hydrogen bonds have an average distance of 1.8 angstrom while C-H center dot center dot center dot O bonds have 2.6 angstrom. The binding energy of the dioxane-methanol complex is found to be a linear function of number of O-H center dot center dot center dot O and C-H center dot center dot center dot O bonds, and hydrogen bond length.