Ionic compound comprising at least one anionic part associated to at least one cationic part M in sufficient number to ensure an electronic neutrality to the compound, characterized in that M is a hydroxonium, a nitrosonium NO+, an ammonium —NH4+, a metallic cation having a valence m, an organic cation having a valence m or an organometallic cation having a valence m, and in that the anionic part is an aromatic heterocycle corresponding to the formula
- in which:
- Y4 and Y5 represent independently from one another a carbonyl group, a sulfonyl group, a thiocarbonyl group, a thionyl group, a —C(═NCN)— group or a —C(═C(CN)2)— group;
- Z represents an electroattractor radical having a Hammett parameter at least equal to that of a fluorine atom;
- each of the substituents RC and RD represent independently from one another a monovalent or divalent organic radical, or is part of a polymer chain, at least one of the substitutents RC and RD being a perfluorinated radical.