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Characterization of dinitroporphyrin zinc complexes by electrospray ionization tandem mass spectrometry. Unusual fragmentations of β‐(1,3‐dinitroalkyl) porphyrins
Author(s) -
Silva E. M. P.,
Domingues M. R. M.,
Barros C.,
Faustino M. A. F.,
Tomé J. P. C.,
Neves M. G. P. M. S.,
Tomé A. C.,
SantanaMarques M. G.,
Cavaleiro J. A. S.,
FerrerCorreia A. J.
Publication year - 2005
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.789
Subject(s) - chemistry , tandem mass spectrometry , protonation , electrospray ionization , nitro , electrospray , substituent , mass spectrometry , medicinal chemistry , alkyl , molecule , mass spectrum , stereochemistry , ion , organic chemistry , chromatography
Abstract The zinc complexes of diaryl bis( p ‐nitrophenyl)porphyrins and β‐(1,3‐dinitroalkyl)tetraphenylporphyrins were studied by electrospray ionization (ESI) tandem mass spectrometry (MS/MS). All porphyrins showed the protonated molecule under ESI conditions. The protonated molecules were induced to fragment and the corresponding ESI tandem mass spectra were analysed. Porphyrins with two p ‐nitrophenyl groups showed, as expected, characteristic fragmentations including either loss of one nitro group, as the major fragment of the tandem mass spectra, and loss of both nitro groups. In contrast, MS/MS of the β‐(1,3‐dinitroalkyl)porphyrins provided interesting and unexpected results such as the absence (or in insignificant abundance) of the ions formed by loss of one nitro group. However, these porphyrins show an abundant fragment due to combined loss of the two nitro groups. Also, the typical β‐cleavage of the alkyl chain is not observed per se , only when combined with loss of HNO 2 or • NO 2 . Instead, α‐cleavage, with loss of the β‐pyrrolic substituent, is the most favourable process. Copyright © 2005 John Wiley & Sons, Ltd.