In:
The Journal of Chemical Physics, AIP Publishing, Vol. 130, No. 12 ( 2009-03-28)
Abstract:
High-pressure infrared measurements were carried out to observe the microscopic structures of two imidazolium-based ionic liquids, i.e., 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide [EMI+(CF3SO2)2N−, EMI+TFSA−] and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)amide [EMI+(FSO2)2N−, EMI+FSA−] . The results obtained at ambient pressure indicate that the imidazolium C–H may exist in two different forms, i.e., isolated and network structures. As the sample of pure EMI+FSA− was compressed, the network configuration is favored with increasing pressure by debiting the isolated form. For EMI+TFSA−/H2O mixtures, the imidazolium C–H peaks split into four bands at high pressures. The new spectral features at approximately 3117 and 3190 cm−1, being concentration sensitive, can be attributed to the interactions between the imidazolium C–H and water molecules. The alkyl C–H absorption exhibits a new band at approximately 3025 cm−1 under high pressures. This observation suggests the formation of a certain water structure around the alkyl C–H groups. The O–H stretching absorption reveals two types of O–H species, i.e., free O–H and bonded O–H. For EMI+TFSA−/H2O mixtures, the compression leads to a loss of the free O–H band intensities, and pressure somehow stabilizes the bonded O–H configurations. The results also suggest the non-negligible roles of weak hydrogen bonds in the structure of ionic liquids.
Type of Medium:
Online Resource
ISSN:
0021-9606
,
1089-7690
Language:
English
Publisher:
AIP Publishing
Publication Date:
2009
detail.hit.zdb_id:
3113-6
detail.hit.zdb_id:
1473050-9
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