We have studied the development of functionalized ionic liquids and control of cation-anion interaction in ionic liquids. Herein we report that utilizing a functionalized ionic liquid with a sulfonate group enable us to carry out greener porphyrin syntheses than ever. Such an ionic liquid shows an effective reactivity and a green property by working as an acidic catalyst which is separated from the reaction medium. Moreover, the specific solvation behaviour in ionic liquids was investigated in order to effectively apply the ionic liquids for various reactions. We have found out that [C4mim] [CS] composed of a bulky camphorsulfonate as an anion provides a ionic liquid. The ES-MS analyses of it revealed a loose interaction between the C4mim+ and the bulky CS-. The [C4mim] [CS] produced an effective endo/exo stereoselectivity in the Diels-Alder reaction. The loose cation-anion interaction of [C4mim] [CS] produces a more naked C4mim+. Therefore the naked C4mim+ can more readily contact the reactant further than its counter-anion. The ES-MS analysis directly demonstrated these interactions.
