Preparation of Mesoverdohemochrome IXα Dimethyl Ester and Mössbauer Spectra of Related Porphyrins

Abstract

Mesobiliverdin IXα dimethyl ester (7) was obtained by hydrogenation of protobiliverdin IXα dimethyl ester (8). Zinc 5-oxamesoporphyrin IX dimethyl ester tetrafluoroborate (6) was prepared by the cyclization of 7 with zinc acetate in acetic anhydride followed by a treatment with aqueous sodium tetrafluoroborate. Bis(pyridine) mesoverdohemochrome IXα dimethyl ester (4) was obtained by the cyclization of 7 with both iron(II) sulfate and iron(III) chloride in acetic anhydride containing a small amount of pyridine. Bis(tosylmethyl isocyanide) mesoverdohemochrome IXα dimethyl ester (5) was prepared by the addition of excess tosylmethyl isocyanide (TsCH2NC) to 4. Both 4 and 5 reacted with ammonia to give iron(III) 5-azamesoporphyrin IX dimethyl ester (10). The Mössbauer spectra of bis(pyridine) verdohemochromes (4, 13, and 14) snowed doublet peaks having parameters of δ=0.41–0.43 mm s−1 and ΔEQ=1.24–1.26 mm s−1, indicating that the oxidation states of the central irons of these complexes are iron(II). Bis(TsCH2NC) verdohemochromes (5, 15, and 17) showed single peaks having parameters of δ=0.21–0.28 mm s−1. Unstable intermediate and stable final bis(TsCH2NC) octaethyl verdohemochromes, obtained by the addition of TsCH2NC to 4, were compared with the 1H NMR and Mössbauer spectra.

Synthesis of Aza-, Oxa-, and Thiaporphyrins and Related Compounds

“… This product was subsequently demetalated with a concentrated solution of HCl, saturated with FeSO 4 in acetic acid, yielding the free base 17 in 63% yield. Similar procedures have also been reported for the preparation of the iron complexes of 5-azaprotoporphyrin IX dimethyl ester, 5-azamesoporphyrin IX dimethyl ester, and 5-aza-2,3,7,8,12,13,17,18-octaethylporphyrin and zinc­(II) complex of 5-azaprotoporphyrin IX dimethyl ester from the corresponding metal complexes of 5-oxoniaporphyrins. The conversion from Fe II complex 18 to Fe III MAP­(Cl) 19 is also shown in Scheme .…”

“…Similar procedures have also been reported for the preparation of the iron complexes of 5-azaprotoporphyrin IX dimethyl ester, 5-azamesoporphyrin IX dimethyl ester, and 5-aza-2,3,7,8,12,13,17,18-octaethylporphyrin and zinc­(II) complex of 5-azaprotoporphyrin IX dimethyl ester from the corresponding metal complexes of 5-oxoniaporphyrins. The conversion from Fe II complex 18 to Fe III MAP­(Cl) 19 is also shown in Scheme . The synthesis of the precursory meso -oxaporphyrins is described in section .…”

Synthesis and Study of the Binuclear μ‐Oxodiiron(III) Complexes of 5‐Monoaza‐ and 5,15‐Diaza‐Substituted β‐Octaalkylporphyrins

“…It is noteworthy that the spectrum of μ-O(FeMAP) 2 is practically identical to the spectrum reported for the Fe III complex of 5-aza-meso-porphyrin IX dimethyl ester dissolved in CH 2 Cl 2 containing 1 % of pyridine (370, 553 and 597 nm). [15] Although the authors believe it to be the chloridoiron(III) complex, the conditions of the described synthetic procedure are more suitable for the formation of the μ-oxo species. Indeed, CH 2 Cl 2 used for extraction and aqueous NaCl used for washing were the only possible (but not probable) sources of chloride.…”

“…The synthesis and spectral properties of μ-oxo dimers formed from the β-alkyl-substituted Fe III porphyrins β-octaethylporphine [μ-O(FeOEP) 2 ] [10][11][12][13] and β-octaethyltetraazaporphine [μ-O(FeOETAP) 2 ] [14] have also been reported. Mononuclear Fe III complexes are also known for forming β-alkylsubstituted meso-monoazaporphyrins [15][16][17][18][19] and meso-diazaporphyrins, [18][19][20][21][22] however, to the best of our knowledge, their binuclear μ-oxo species have not been characterised. In the present work we report the preparation of new μ-oxodiiron(III) complexes formed from β-alkyl-substituted 5-monoaza-and 5, 15-diazaporphyrins …”

Tetrabenzodiazaporphyrin: the semiconducting hybrid of phthalocyanine and tetrabenzoporphyrin

“…Monoazaporphyrins have been prepared by cyclization of tetrapyrrole such as biladienes [19,20] or mesobiliverdin [21,22]. Diazaporphyrins have been also prepared by the reaction of dibromodipyrromethene with sodium azide [23,24].…”