Characterization of sulfonated phthalocyanines by mass spectrometry and capillary electrophoresis

Abstract

We report the characterization of sulfonated phthalocyanines using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. In general, sulfonated phthalocyanines were found as aggregates in capillary electrophoresis separations, even at low concentration. Separations were much better at pH 9.0 than at pH 2.5. The addition of β-cyclodextrin did not alter the electropherograms significantly. The electropherograms of commercially available copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid and 4,4',4″,4‴-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. In general, MALDI gave better results than ESI. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Sulfonated tetraphenylporphyrin derivatives were used as standards for mass spectrometry and to estimate the effect of net charge on the capillary electrophoresis migration time for sulfonated tetrapyrroles. Clean separation of the sulfonated tetraphenylporphyrin derivatives [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3) and 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2a)] was observed by capillary electrophoresis.

Sulfonated naphthyl porphyrins as agents against HIV-1

“…As reported previously, the negative ion MALDI (CHCA matrix) of T2Nap5S showed a very simple, clear pattern for the tetrasulfonic acid (1134, M À ) and its mono-, di-and trisodium salts [38]. The pentasulfonic acid (1214, M À ) and its mono-, di-, tri-, and tetrasodium salts were also seen.…”

“…This may reflect the conformations of the 1-naphthyl groups, which extend above and beneath the porphyrin plane, reducing selfstacking. Previous work has shown that self-stacking reduces the CE separation of tetrapyrroles [38]. In the 2-naphthyl series, separation was aided significantly by the addition of cyclodextrins; b-and c-cyclodextrins gave quite different patterns.…”

“…Simple mixtures of sulfonated porphyrins can be separated as a function of charge by capillary electrophoresis [36][37][38]. The sulfonated naphthyl porphyrins are mixtures of numerous compounds, however, making separation more difficult.…”

Highly Selective Detection of Trace Copper(II) Using Bathocuproinesulfonate by Flow-Injection Electrospray Ionization Mass Spectrometry

“…We used aromatic chelating agents, such as tetrakis(4-carboxyphenyl)porphyrin (TCPP) and tetraphenylporphyrin tetrasulfonate (TPPS), which are water-soluble porphyrins used for the fluorescence detection of metal ions, 8,9 and bathocuproinesulfonate (BCS), which is a phenanthroline that selectively binds copper ions 10 ( Fig. S1, Supporting Information).…”

The constitutes and isomer distribution of di-(potassium sulfonate)-di-phthalimidomethyl phthalocyanine zinc

“…Besides, the cis-and trans-isomers with identical sulfonated groups can also be distinguished by their retention time, and the trans-isomer should pass through the column firstly. Dixon et al [10] tried to separate some sulfonated phthalocyanines with capillary electrophoresis method, but the result was unsatisfactory. To our knowledge so far, baseline separation of such substituted phthalocyanine isomers has not been achieved in the literature [11 14] .…”