Spectroscopy of Support and IL

IL is grafted on silica [4]. In this work of Yamaguchi et al, an additional analysis of MAS NMR is given, which confirms that the IL, immobilized as an SILP system, results in the same signals as the IL without support. The MAS NMR spectrum of the PFg anion shows a signal at 103 ppm with a Jp.p of 708 Hz. 

The main conclusion of these findings is that imidazolium-containing ILs can be bound on a silica surface without decomposition of the organic cation. 

This behavior is explained in a way that the confined IL, as compared with bulk IL, below about 270 K, shows liquid-Uke behavior whereas bulk IL already crystallizes. 

The phenomenon of melting point depression was not only investigated with ionogel systems but also with SILP systems that were prepared by a standard procedure according to the hterature [8]. The use of controlled pore glass (CPG) as support shows impressively the melting point depression of ILs in confinement (9). 

By using the Carr- Purcell-Meiboom-GiU (CPMG) echo sequence, it is possible to distinguish between the solid and the liquid state by using HR NMR spectroscopy for liquids. This temperature-dependent method is also known as cryoporometry. 

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