Microscopic Solvation Structure of Glucose in 1-Ethyl-3-methylimidazolium Methylphosphonate Ionic Liquid

The solvation structure of glucose in 1-ethyl-3-methylimidazolium methylphosphonate, [C(2)mIm(+)] [CH3(H)PO3-] ionic liquid and the liquid structure of the neat [C(2)mIm(+)] [CH3(H)PO3-] were investigated by high-energy X-ray diffraction (HEXRD) experiments with the aid of inolecular dynamics (MD) simulations. In neat [C(2)mIm(+)] [CH3(H)PO3-], a specific interaction between the cation and anion is found, that is, the oxygen atoms within CH3(H)PO3- are hydrogen bonded with the hydrogen of the C2 position within C2mIm+. In glucosei[C(2)mIm(+)] [CH3(H)PO3-] solutions, a significant peak is observed at 2.6 A in experimental radial distribution functions and is enhanced with increasing glucose concentration. It is found from MD simulations that the peak originated from the nearest-neighbor intermolecular interaction between glucose and the anion in [C(2)mIm(+)] [CH3(H)PO3-]. The atom atom pair correlation function derived from MD results shows that hydroxyl groups of glucose interact with oxygen atoms within CH3(H)PO3- through the hydrogen bonds. The intermolecular hydrogen bonds coexist with the intramolecular hydrogen bond in a glucose molecule. We conclude that glucose is easy to form a hydrogen bond with a polar CH3(H)PO3- anion; however, rupture of intrarnolecular hydrogen bonds within glucose is not enough in the ionic liquid.