Spectroscopic and computational studies of aqueous ethylene glycol solution surfaces.
The combination of Monte Carlo, ab initio, and DFT computational studies of ethylene glycol (EG) and EG-water hydrogen-bonding complexes indicate that experimental vibrational spectra of EG and EG-water solution surfaces have contributions from numerous conformations of both EG and EG-water. The computed spectra, derived from harmonic vibrational frequency calculations and a theoretical Boltzmann distribution, show similarity to the experimental surface vibrational spectra of EG taken by broad-bandwidth sum frequency generation (SFG) spectroscopy. This similarity suggests that, at the EG and aqueous EG surfaces, there are numerous coexisting conformations of stable EG and EG-water complexes. A blue shift of the CH2 symmetric stretch peak in the SFG spectra was observed with an increase in the water concentration. This change indicates that EG behaves as a hydrogen-bond acceptor when solvated by additional water molecules. This also suggests that, in aqueous solutions of EG, EG-EG aggregates are unlikely to exist. The experimental blue shift is consistent with the results from the computational studies.
Hommel
Elizabeth L
EL
Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, USA.
Merle
John K
JK
Ma
Gang
G
Hadad
Christopher M
CM
Allen
Heather C
HC
D003198:Computer Simulation; D019855:Ethylene Glycol / Q000737:chemistry*; D008956:Models, Chemical; D009010:Monte Carlo Method; D011789:Quantum Theory; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013055:Spectrophotometry, Infrared / Q000379:methods; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D012996:Solutions; D014867:Water; D019855:Ethylene Glycol