Spectroscopic Assessment of Intra- and Intermolecular Hydrogen Bonding in Ether-Functionalized Imidazolium Ionic Liquids.
Helen J ZengMark A JohnsonJasodra D RamdihalRawlric A SumnerChanele RodriguezSharon I Lall-RamnarineJames F WishartPublished in: The journal of physical chemistry. A (2019)
Functionalization of the imidazolium (Im+) cationic component of ionic liquids (ILs) with ether chains affords the possibility of tuning their properties through manipulation of the resulting interion and intramolecular interactions. Herein, we quantify these interactions at the molecular level through analysis of the vibrational spectra displayed by size-selected and cryogenically cooled ions. These spectra are obtained using the "tagging" approach carried out with photofragmentation tandem mass spectrometry. In the isolated cations, we find that the oxygen atom on the ether chain binds exclusively to the acidic C(2)H position on the Im+ ring. Upon complexation with BF4- to form the ternary (ether-MIm+)2(BF4-) cation, however, the less acidic C(4,5)H groups also participate as contact points for the ionic assembly, in contrast to the behavior of the closely related (EMIm+)2(BF4-) system. These experimental results support the conclusions derived from earlier X-ray scattering and molecular dynamics results on bulk ILs regarding interactions with the ring CH groups and their implications on tuning the viscosities of this class of functionalized ILs.
Keyphrases
- ionic liquid
- molecular dynamics
- density functional theory
- tandem mass spectrometry
- room temperature
- quantum dots
- ultra high performance liquid chromatography
- energy transfer
- high performance liquid chromatography
- high resolution
- liquid chromatography
- simultaneous determination
- gas chromatography
- magnetic resonance
- solid phase extraction
- molecularly imprinted
- molecular docking
- computed tomography
- molecular dynamics simulations
- high resolution mass spectrometry