MS/MS Fragmentation Behavior Study of meso-Phenylporphyrinoids Containing Nonpyrrolic Heterocycles and meso-Thienyl-Substituted Porphyrins

Abstract

Free base and cobalt(II) complexes of six meso-tetraphenylporphyrinoids containing nonpyrrolic heterocycles and of three meso-thienylporphyrins were investigated using electrospray ionization tandem mass spectrometry (ESI-MS/MS). Their fragmentation was studied in a quadrupole ion trap as a function of the porphyrinoid macrocycle structure and compared with the fragmentation behavior of the benchmark compound meso-tetraphenylporphyrin. In situ oxidation of the neutral cobalt(II) complexes under ESI conditions produced singly charged cobalt(III) porphyrinoid ions; the free bases were ionized by protonation. For the porphyrinoids with an intact porphyrin core, the major fragmentation pathways observed were the losses of the meso-substituent (for meso-phenyl groups) and characteristic fragmentations of one or more meso-substituents (for the meso-thienyl group). Complex fragmentation pathways were observed for porphyrinoids with modifications to the porphyrin core but chemically reasonable structures could be assigned to most fragments, thus delineating general patterns for the behavior of pyrrole-modified porphyrins under CID conditions. ᅟ

Comprehensive analysis of metalloporphyrins via high irradiance laser ionization time-of-flight mass spectrometry

“…16,17 LI-TOFMS may also be considered for analysis of organic compounds, as this technique was used to successfully characterize benzoylferrocene. 18 In this report, we focus on an LI-TOFMS analytical strategy, different from those methods mentioned, [5][6][7][8][9][10] for the analysis of metalloporphyrins. Comprehensive information on metallic/nonmetallic elements, characteristic fragments, and intact molecules of analytes can be selectively acquired through the variation of helium buffer gas pressure in the ion source.…”

Gas‐Phase Transformation of Fluorinated Benzoporphyrins to Porphyrin‐Embedded Conical Nanocarbons

“…By contrast, the pathway followed by [ 1Co ] +. predominantly features the desired cyclization reaction, and, contradictory to the literature, the loss of pentafluorobenzene (C 6 F 5 H) is negligible (Figure b). The loss of one or two hydrogen atoms is not observed for the metalated species.…”

Oxazolochlorins. 14.

“…replacement of a pyrrole by, for example, an oxazole or imidazole (Akhigbe, Peters et al, 2011;Akhigbe et al, 2013), or even reactions that involve replacement of H atoms by substantially larger substituents [such as oxidation to a diol, as in (3A) or (3B), or to a porpholactone, as in (4A) and (4B)], do not significantly change the shape of the molecules as a whole. However, optical (UV-vis and fluorescence) and chemical properties may be altered dramatically as a result of these modifications (Brü ckner et al, 2012;Mishra et al, 2014). Since the modified molecules often still exhibit nearly the same shape and symmetry as the parent porphyrin, they frequently assemble during crystallization like the porphyrins.…”