Ionic liquids with 4-cyanopyridinium-based cations have been shown to form exceptionally colourful charge-transfer complexes with polyaromatic moleules such as naphthalene. Immobilisation of the ionic liquids through confinement within silica ionogels forms the basis for potentially new optical sensing technologies. The objectives of this proposal is to provide information on (i) the structure of the silica-confined ionic liquid, which will be compared with previous bulk ionic liquid data, and (ii) to explore the differences in the response of such ionogels to the two aromatic liquids, 1-methylnaphthalene and toluene, where a coloured charge transfer complex is formed in the former case and not in the latter.