Two‐dimensional Raman spectroscopy study of ionogel phase formation in long‐chain ionic liquid/water systems

Abstract

The phase behavior of the imidazolium‐based room temperature ionic liquids (RTILs) 1‐decyl‐3‐methyl‐imidazolium bromide and chloride ([C10mim][Br], [C10mim][Cl]) were studied by 2D Raman correlation spectroscopy and principal component analysis. The hydrogen‐bonded network changes and the liquid crystalline ionogel phase formation were observed when water content was continuously increased in the system, and the Raman shift of C–H stretching modes in spectra was monitored. The extent of liquid crystalline ionogel phase was determined from the discontinuities in the concentration dependencies. The focus to the Raman bands originated from the imidazolium ring C–H stretching mode region (3000–3200 cm−1) when water content in the IL was increased allowing to determine the lower border of ionogel phase formation in RTIL/water systems. The upper border of the ionogel phase was determined when main attention was carried out to the Raman bands originated from the O–H stretching vibration region (3200–3800 cm−1). The hypothesis of weaker hydrogen bonds involving the C(4)‐H and C(5)‐H groups and stronger hydrogen bonds of the C(2)‐H groups was supported by Raman results. Copyright © 2016 John Wiley & Sons, Ltd.

Synergy between silk fibroin and ionic liquids for active gas-sensing materials

“…In particular, C 10 mimCl is reported to present unique self-assembly characteristics [ 23 ]. Moreover, a water content above 3% w/w can promote a H-bonded network and liquid crystalline gel phase with C 10 mimCl [ 26 ], which is the case in our work (water content 6.9% w/w). The C 10 HC gel presented a surface topography of stripes but with a higher RMS roughness (3.2 ​nm) when compared to C 10 F. These results suggest that the IL self-assembling properties are predominant in the final hierarchical order of the fibroin ionogel, and that fibroin affects the organization of the IL creating smaller ordered clusters, suggesting that fibroin chains are interspersed in the IL supramolecular assemblies.…”

Water in ionic liquids: Raman spectroscopic studies

“…Raman spectroscopy is also used to study the unprecedented enhancement of water content of hydrophobic IL when mixed with zwitterion [ 11 ] and the state of the water molecules in liquid crystalline ion‐gel phase in IL/water mixtures. [ 12,13 ] Recently, it has been shown that Raman spectroscopy is useful to study the enhancement of CO 2 capture in IL/water binary mixtures. [ 14 ]…”

“…[1] Raman spectroscopy is also used to study the unprecedented enhancement of water content of hydrophobic IL when mixed with zwitterion [11] and the state of the water molecules in liquid crystalline ion-gel phase in IL/water mixtures. [12,13] Recently, it has been shown that Raman spectroscopy is useful to study the enhancement of CO 2 capture in IL/water binary mixtures. [14] In this short review, we have not covered the Raman studies of just ILs (cation and anion) and DFT of ILs as there are some excellent recent reviews that are available on these topics.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…Kausteklis, Balevicius, and Aleksa carried out a two‐dimensional Raman study of ionogel phase formation in long‐chain ionic liquid/water systems. Their hypothesis of weaker hydrogen bonds involving the C(4)H and C(5)H groups and stronger hydrogen bonds of the C(2) H groups was supported by Raman results . Lou et al described a simple drop‐and‐detect method using porous alumina ceramics as platforms for rapid SERS spectroscopy.…”

“…Their hypothesis of weaker hydrogen bonds involving the C(4)-H and C(5)-H groups and stronger hydrogen bonds of the C(2) -H groups was supported by Raman results. [224] Lou et al described a simple drop-and-detect method using porous alumina ceramics as platforms for rapid SERS spectroscopy. Their proposed drop-and-detect method was demonstrated in relevant way by the quantitative detection of trace levels of melamine in liquid milk achieving a lowest detectable concentration of 0.1 mg/L, indicating its advantages of simplicity and efficiency for practical SERS applications.…”