Electrospray negative ionization mass spectrometry of polyamides containing N‐methylpyrrole and N‐methylimidazole

Abstract

Electrospray negative ionization mass spectrometry of polyamides containing N-methylpyrrole and N-methylimidazole Polyamides containing N-methylpyrrole (Py) and N-methylimidazole (Im) have attracted considerable attention from biological chemists because they can recognize and bind in the minor groove of DNA with high affinity and specificity. Furthermore these polyamides can permeate living cell membranes and have the potential to control specific gene expression. 1,2 We have previously Scheme 1. Main fragmentation models of the negative ion polyamides.

Amino‐catalyzed fragmentation characteristics of polyamides containing N‐methylpyrrole and N‐methylimidazole by electrospray negative ionization mass spectrometry

“…1, the mass spectra of [M–H] − ions of a 2 , b 2 , c 2 , d 2 at m/z 383, 482, 369, 454 showed characteristic [M–H–82] − ions at m/z 301, 400, 287, 372, respectively. Of course, these cleavages are also a 1 cleavages accompanied by a hydrogen atom migration to a carbon atom as reported in the literature 15. The MS 3 and MS 4 fragmentation characteristics of polyamides a 2 , b 2 , c 2 , d 2 were also investigated; after [M–H–82] − ions further lost CO 2 , C 2 H 5 OH or H 2 O, fragment ions corresponded to [M–H–82–CO 2 ] − , [M–H–82–C 2 H 5 OH] − or [M–H–82–H 2 O] − .…”

“…At the same time, these polyamides were analyzed by electrospray ionization tandem mass spectrometry (ESI‐MS n ) with low‐energy collision‐induced dissociation (CID) in order to establish a general structural elucidation of correlative derivatives. There is some information reported on cleavage patterns for polyamides in positive and negative modes 13–15. We report herein a study of the different negative fragmentations of polyamides containing N ‐methylpyrrole ( a 1 , b 1 , c 1 , d 1 ) and polyamides containing N ‐methylimidazole ( a 2 , b 2 , c 2 , d 2 , e , f ).…”

Mass Spectrometry of Synthetic Polymers

“…Yaun and Zhou used ESI and MS n (n ) 2-6) to study the fragmentation mechanism of polyamides containing N-methylimidazole and N-methylpyrrole (77). Wang et al also studied the ESI fragmentation of a series of polyamides containing N-methylpyrrole and N-methylimidazole but in the negative ion mode (78). ESI of polyesters composed of isophthalic acid and neopentyl glycol produced carboxylate anions in the negative ion mode and Na + cationized oligomers in the positive ion mode (79).…”