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Electrospray tandem mass spectrometry of 2 H ‐chromenes
Author(s) -
Domingues M. Rosário M.,
Domingues Pedro,
Oliveira M. Manuel,
Carvalho Luis H. M.,
OliveiraCampos Ana F.,
Ferrer Correia António J.
Publication year - 2004
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1713
Subject(s) - chemistry , fragmentation (computing) , tandem mass spectrometry , carbocation , protonation , collision induced dissociation , electrospray , deuterium , stereochemistry , mass spectrometry , electrospray ionization , medicinal chemistry , ion , organic chemistry , chromatography , physics , quantum mechanics , computer science , operating system
Several 2 H ‐chromenes derived from carbazoles were analyzed by electrospray tandem mass spectrometry. The 2 H ‐chromenes constitute an important class of compounds that exhibit photochromic activity. The fragmentation pathways of the protonated molecular species [M+H] + were studied, and main fragmentation pathways of these compounds were identified. Fragmentation pathways of [M+D] + ions were also studied in order to obtain information about the location of the ionizing proton or deuteron. It was found that the proton is not preferentially located on the nitrogen atom. The charge is preferentially located as a tertiary carbocation, resulting from the uptake of the proton (or deuteron) by the zwitterionic open structure of the chromenes. The major fragmentation occurred by cleavage of the γ ‐bond relative to the carbocation center, leading to a fragment at m/z 191 (C 5 H 11 +or C 14 H 9 N + ), which are the most abundant fragment ions for almost all compounds. The presence of substituents in the chromene ring does not change this behavior. Other observed common fragmentation pathways included loss of CH 3 .(15 Da), loss of CO (28 Da), combined loss of CO and CH 3 (43 Da), and loss of the phenyl ring via combined loss of C 6 H 4 and CH 3 .(−91 Da) and combined loss of C 6 H 6 and CO (−106 Da). Copyright © 2004 John Wiley & Sons, Ltd.