Collision-induced dissociation of imidazolium-based zwitterionic liquids

Fragmentation pathways of some imidazolium based zwitterionic liquids-3-(3-alkyl-1-imidazolio)- propane sulfonates and 3-(2-methyl-3-alkyl-1-imidazolio)-propane sulfonates -- have been studied by tandem electrospray mass spectrometry and collision-induced dissociation. The relative abundances of the lowest energy fragment ions depend on the length of the alkyl chain at the (II)N of the imidazolium ring and the cone voltage. The first fragment ions originate from the scission of C(non aromatic)-N bond of compounds investigated, but with increasing collision energy, scission of C-C bonds occurs. Aggregates of the general formula [(M + H)(x) + (M)(y)](+) (x;y = 1-2) formed. Methyl substituted zwitterionic liquids show higher molecular stability than 3-(3-alkyl-1-imidazolio)-propane sulfonates.