Electrospray ionization (ESI) tandem mass spectrometric analysis of meso-tetrakis(heptafluoropropyl)porphyrin

Abstract

The results of an electrospray ionization (ESI(ϩ) and ESI(Ϫ)) collision-induced fragmentation investigation of meso-tetrakis(heptafluoropropyl)porphyrin (T F HP) are reported. The fragmentation patterns of T F HP show, in both ionization modes, the formation of fragments with direct covalent meso-alkyl-to-␤-linkages on elimination of HF. In addition, in the ESI(ϩ) mode, the losses of perfluoroalkyl radicals are observed. A detailed analysis of the fragmentation patterns allows conclusions to be drawn on the identification of the fragment species. Comparable cyclized products were previously produced using radical-initiated solution- In particular, the mesoperfluoroalkylporphyrins have proved useful in, for example, the design of synthetic monooxygenase mimicks [6]. In addition, their potential in both photodynamic therapy and in the in vivo imaging by fluorescence and 19 F NMR (nuclear magnetic resonance) spectroscopy was evaluated [7].Recently, the groups of Guo and Chen described, inter alia, the functionalization of meso-arylporphyrins with meso-fluoroiodo-alkanes (1) or fluorochloro-alkanes (2). Radical-induced deiodination or debromination resulted in the formation of terminal radicals that efficiently ring-closed with the neighboring ␤-positions to form products 3 and 4, respectively (Scheme 1) [8,9]. Thus, a range of fused ring products enclosing five-and six-membered rings were prepared. These findings prompted the question whether meso-perfluoroalkylporphyrins such as meso-tetrakis(heptafluoropropyl)-porphyrin (T F HP) also undergo similar cyclizations. This study will answer this question affirmatively.Here, we report the analysis of T F HP by tandem electrospray ionization (ESI) mass spectrometry in the positive and negative mode. Using collision-induced fragmentation techniques, we find that rich fragmentation patterns in positive and negative ionization modes are observed. Next to the expected losses of radical fragments, HF eliminations are observed, which we attribute to the formation of polycyclic systems containing meso-alkyl-to-␤-fusions. A detailed analysis of the spectra allows some conclusions to be drawn as to the nature of these products.

Observation of phenyl-fused porphyrinoids during the ESI mass spectrometric analysis of meso-pentafluorophenyl-substituted porphyrin and corrole

“…Further, as the loss of aryl radical fragments demonstrates, radical pathways also cannot be excluded. In fact, we have observed the HF-elimination in meso-heptafluoropropyl-substituted porphyrins under ESI conditions that is, under ESI(ϩ) conditions, intermingled with a radical fragmentation pathway of the meso-alkyl groups [35].…”

“…Electrospray ionization (ESI) mass spectrometry (MS) is becoming a popular technique for the analyses of porphyrins [25][26][27][28][29][30][31][32][33][34][35].…”

Characterization of isomeric cationic porphyrins with β-pyrrolic substituents by electrospray mass spectrometry: The singular behavior of a potential virus photoinactivator

“…In the case of the loss of H 2 , a similar cyclization with elimination of an HF molecule and formation of a fivemembered ring was described for pyrrolidine-fused cationic°chlorins°and°isobacteriochlorins° [22],°and°for meso-tetrakis(heptafluoropropyl)porphyrin° [13]. …”

“…In particular, the Herpes simplex virus is one of the most common agents responsible for viral infections in man [5]. From preliminary virus inactivation studies carried out with Herpes simplex virus type 1 (HSV-1) using the cationic porphyrins 1 and 2 (Scheme 1), we have observed that despite their structural resemblance and their similar photocytotoxicity profiles, Compound 1 was very effective in the photoinactivation of the virus, whereas Compound 2 displayed no virucidal effect in the same conditions [6].Electrospray ionization mass spectrometry (ESI-MS) was successfully applied to characterize porphyrins as early as 1991 [7] and both ESI-MS [8 -11] and tandem mass spectrometry (ESI-MS/MS) [12,13] have been used to study neutral and cationic porphyrins since then. We wanted to know if the two porphyrin isomers, 1 and 2, could be differentiated by ESI-MS/MS and if the informa-…”

“…Electrospray ionization mass spectrometry (ESI-MS) was successfully applied to characterize porphyrins as early as 1991 [7] and both ESI-MS [8 -11] and tandem mass spectrometry (ESI-MS/MS) [12,13] have been used to study neutral and cationic porphyrins since then. We wanted to know if the two porphyrin isomers, 1 and 2, could be differentiated by ESI-MS/MS and if the informa-tion obtained on their gas-phase behavior could be relevant to understand their virucidal properties.…”