- Protonation-deprotonation equilibria in tetrapyrroles Part 4: Mono- and diprotonations of deutero-, hemato-, meso-, and protoporphyrin IX dimethyl esters in methanolic hydrochloric acid
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The N-protonations in the deutero, hemato, meso and protoporphyrin IX dimethyl esters (DME) were investigated by spectrophotometric titrations using HCl as the acid and methanol as the solvent. Two spectroscopically different protonated species were observed for each porphyrin DME in addition to the neutral form. These were assigned to the N-protonated monocation and dication. There were no difficulties encountered in observing the monocation formation in the HCl-MeOH system. Very sharp isosbestic points were characteristic of each protonation stage. The pK3 values for the porphyrins in the above order were 3.23, 4.70, 2.93 and 3.37; the pK4 values were 2.48, 2.62, 2.41 and 2.64, respectively. For all porphyrins studied, no further spectral changes were observed after the dication was completely formed. This was interpreted as indicating that the formation of more highly protonated species is not possible in fullydelocalized porphyrins possessing the 18 π-electron [18]diazaannulene delocalization pathway. When the titration was performed on the free dicarboxylic acid porphyrins, aggregation obscured the first protonation step and no clear monocation spectrum could be distinguished. However, also in that case the titration ended up to a UVvis spectrum typical of the dication and the effect of aggregation on the pK4 values was negligible. The UVvis spectrometric parameters are given for the neutral forms and for the protonated species of the porphyrin DMEs. The results are discussed in terms of the NH tautomerization connected to the π-electron delocalization pathway (aromaticity), which tends to hinder outofplane distortions in the porphyrin plane, and in terms of solvation and counterion stabilization of the protonated forms.
- Hynninen, Paavo H.
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p. 385 - 395
(2015/05/20)
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- Synthesis and structure of five or six-coordinate manganese deuteroporphyrin-niacin dyads with intramolecular axial pyridine
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Deuteroporphyrin-niacin dyads with different chain lengths have been synthesized by modification of the propionate side chains of hemin. When a manganese ion was inserted into the porphyrin core, the UV spectral shift of manganese deuteroporphyrin-niacin dyads were experimentally demonstrated to mainly originate from the intramolecular coordination. In order to elaborate the intramolecular coordination, the spectra of single manganese porphyrin complexes in CH2Cl2 solution were measured and compared to that of the addition of axial ligands (pyridine and methyl nicotinate). Among all the synthetic dyads, the compounds of 2,7,12,18-tetramethyl-13,17-di(3- hydroxypropyl nicotinate) porphyrin and 2,7,12,18-tetramethyl-13,17-di(3- aminoethyl nicotinate) porphyrin manganese bearing the short chains did not show intramolecular coordination of the terminal base on the metal ion. Other three compounds of the niacin moiety indirectly bonded to the propionate side chains of manganese porphyrin through the diols linkage exhibited optical spectra characteristic of five or six-coordinate manganese complexes. These results indicate that the niacin groups' access to the Mn(III) center depended on the chain lengths.
- Sun, Chengguo,Hu, Bingcheng,Zhao, Donghui,Liu, Zuliang
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p. 130 - 137,8
(2020/08/20)
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- A facile synthesis of deuteroporphyrins derivatives under ultrasound irradiation
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A facile, efficient and general method for preparing deuteroporphyrin derivatives by using concentrated H2SO4 and alcohol under ultrasound irradiation has been developed. A series of new deuteroporphyrin derivatives bearing different propionic ester groups have been synthesized in good yields starting from readily accessible deuterohemin. The characterization of these compounds confirms the synthetic methodology. Compared with conventional methods, the main advantages of the present procedure are shorter reaction time and higher yields.
- Hu, Bingcheng,Zhou, Weiyou,Tang, Ying,Huang, Chengmei,Liu, Zuliang
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experimental part
p. 288 - 291
(2010/12/25)
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- Synthesis of tetrapyrrole nitrogen mustards with potential anti-tumor activities
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Eight porphyrin nitrogen mustards and six meso-tetraphenylporphin nitrogen mustards were synthesized. Most of the compounds possess both the chemotherapeutic and photochemotherapeutic effects on tumor.
- Chen, Zhi-Long,Wan, Wei-Qin,Chen, Jing-Rong,Zhao, Fang,Xu, De-Yu
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p. 1739 - 1745
(2007/10/03)
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- Synthesis and Reactivity of 131,132,171,172-Tetradehydrodeuteroporphin
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Die 13,17-Propionsaeure-methylester-Seitenketten des Deuteroporphyrin-dimethylesters (1a) wurden mit Phenylselenobromid zu 1b dehydriert.Die 12,18-Methylgruppen tauschten in Deuteriomethanol mit Natriummethoxid Wasserstoff gegen Deuterium aus.
- Fuhrhop, Juergen-Hinrich,Lehmann, Thomas
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p. 1386 - 1389
(2007/10/02)
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- Carbon-5 Regiospecific Synthesis of Deuteroporphyrin IX
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Benzyl 3-(ethoxycarbonyl)-4-methyl-2-pyrrolecarboxylate was formylated with dimethylformamide (DMF)-phosphorous oxychloride, and the 5-formylpyrrole was obtained in 50percent yield.It was reduced with sodium borohydride to the alcohol, which was condensed with benzyl 3-methyl-4-(ethoxycarbonyl)-2-pyrrolecarboxylate to afford dibenzyldipyrrylmethane in good yield.The latter was transformed into its 5,5'-diformyl derivative which when condensed with bis-4-methylpyrryl>methane afforded the 3,8-bis(ethoxycarbonyl)deuteroporphyrin IX dimethyl ester in 40percent yield.Decarboxylation of the latter in hot hydrochloric acid gave deuteroporphyrin IX (isolated as its dimethyl ester) in 50percent yield.
- Rezzano, Irene,Buldain, Graciela,Frydman, Benjamin
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p. 3059 - 3063
(2007/10/02)
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- PETROPORPHYRINS - II. THE PRESENCE OF PORPHYRINS WITH EXTENDED ALKYL SUBSTITUENTS
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The vanadyl porphyrins from Boscan oil (Cretaceous, W.Venezuela) were isolated as 3 fractions, and degraded to maleimides (1H-pyrrole-2,5-diones) by chromic acid.Analysis of the products by GC-MS, using multiple ion detection to enhance sensitivity, revealed a major homologous series of 3-Me components with n-alkyl side chains extending to C11, and a minor series with branched alkyl side chains, the Me branch being at C-1.The origin of the extended alkyl groups is discussed.
- Martin, J.,Quirke, E.,Shaw, George J.,Soper, Paul D.,Maxwell, James R.
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p. 3261 - 3268
(2007/10/02)
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