Solvation of D-glucose in water and in room-temperature ionic liquids (RTILs) based on 1-ethyl-3-methylimidazolium (EMI+) cation are studied via molecular dynamics (MD) simulations using OPLS force field parameters. For RTILs, four different anionic species, BF4-, Cl-, dimethylphosphate (DMP-) and acetate (Ac-), are considered to investigate the dependence of glucose solubility on RTIL anions. In agreement with previously reported experimental and MD results in water, �-D-glucose is found to be more soluble than a-D-glucose in all five solvents. In RTILs, the difference in their solvation free energy is 2-3 kT. It is also found that D-glucose solubility varies significantly with the RTIL anionic species; specifically, it increases in the order BF4-, Cl-, DMP- and Ac-, viz., with increasing anion basicity. With the exception of BF4-, D-glucose solubility in RTILs is considerably higher than that in water. This is attributed to strong H-bond formation between hydrogen atoms of glucose OH groups and RTIL anions. Vibrational spectra of glucose OH groups are analyzed in conjunction with structures of their H-bonds with RTIL anions. Peak structures of the spectra provide revealing insights into differing H-bond structures, such as one-to-one vs bifurcated H-bonds, that can interconvert to each other. In addition, frequency shifts of glucose OH vibrations show a good correlation with glucose solubility. This further supports the view that H-bond interactions between glucose OH groups and RTIL anions play an important role in glucose solubility.

Solvation of D-glucose in ionic liquids and water

248th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.