Electrospray ionization of porphyrins using a quadrupole ion trap for mass analysis

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.

Section: Resultsmentioning

confidence: 99%

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

Lau

Sadı́lek

Khalil

et al. 2005

“…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].…”

mentioning

confidence: 99%

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

Lau

Sadı́lek

Gouterman

et al. 2006

The results of ESI(ϩ) and ESI(Ϫ) mass spectrometry/mass spectrometry investigations of meso-tetrakisphenylporphyrin (TPP) and meso-trisphenylcorrole (TPC) in comparison with their meso-tetrakis(pentafluorophenyl)-substituted analogs T F PP and T F PC are reported. The fragmentation patterns of TPP and TPC show the expected loss of meso-aryl radicals. Analyzing the meso-pentafluorophenyl substituted analogs T F PP and T F PC, we found ESI(Ϫ) to be an excellent ionization mode. Rich and well-defined HF-elimination fragmentation patterns unique to the presence of meso-tetrafluorophenyl groups and evocative for the formation of fragments with direct covalent o-phenyl-to-␤-linkages are observed. A computation of the feasibility and relative energies of the resulting species corroborates the interpretation of the experimental findings. The computations indicate the presence of cooperative interactions between the linkages that direct the linkage formations to occur in a unidirectional fashion. MS/MS/MS experiments also provide indications for the regioselectivity of the fusions. Our observations further detail earlier reports of similar HF-eliminations and allow a generalization of the findings. The results presented may also point to strategies towards the bulk synthesis of novel porphyrinoid structures. (J Am Soc Mass Spectrom 2006, 17, 1306 -1314

“…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-…”

mentioning

confidence: 99%

“…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.…”

mentioning

confidence: 99%

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

Izquierdo

Barros

Santana-Marques

et al. 2007

Electrospray ionization mass spectrometry (ESI-MS) and tandem mass spectrometry (ESI-MS/ MS) have been used to differentiate the 2-and 4-methylpyridyl isomers of free-base and metallated cationic ␤-vinylpyridylporphyrins. The analysis by ESI-MS/MS of the deuterated analogs and semiempirical calculations of structural and electronic parameters were also undertaken. The two free-base isomers are easily differentiated by ESI-MS/MS but the presence of a metallic center renders differentiation of the metallated isomers less effective. The data acquired show that of all the studied compounds, the free-base 2-methylpyridyl isomer, which was operative in the in vitro photoinactivation of Herpes simples virus, has a different gas-phase behavior. Local distortion of the macrocycle due to the presence of the ␤-vinylpyridyl substituent occurs for all the compounds, but a different electron density distribution can account for the observed gas-phase behavior of this potential virus photoinactivator. (J Am Soc Mass Spectrom 2007, 18, 218 -225 Viruses are responsible for a large number of infectious diseases. 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-