ESI-MS characteristics of N-methylpyrrole polyamide/bis-cyclen conjugate

The study of the dissociation of the protonated molecular species [M+H]+ and selected fragment ions allowed proposals for the main fragmentation pathways of the title compound. The main fragmentation pathways occur by the cleavage of the C–CO bonds between N-methylpyrrole and carbonyl groups. Because of the introduction of bis-cyclen into the polyamide, the most striking feature of the MS/MS spectra is the prevalence of ring contractions. Electrospray ionization is proven to be a good method for the structural characterization and identification of these kinds of compounds.