Hoch‐ und perchlorierte <i>meso</i>‐Tetraphenylporphyrine

Wijesekera, Tilak P.; Matsumoto, A.; Dolphin, David; Lexa, Doris

doi:10.1002/ange.19901020918

Cited by 29 publications

(12 citation statements)

References 11 publications

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“…The presence of electron-withdrawing substituents at the β-pyrrole positions on the macrocycle is wellknown to increase the metal-centered redox potential of perhalogenated porphyrins [2,29,30,[53][54][55]. In fact, the Mn(III)/Mn(II) redox potential for MnBr 8 T2PyPCl is 0.38 V higher than the potencial measured for its first-generation analogue MnT2PyPCl.…”

Section: Catalytic Studiesmentioning

confidence: 87%

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

Rebouças

Carvalho

Idemori

2002

J. Porphyrins Phthalocyanines

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The synthesis of 2, 3, 7, 8, 12, 13, 17, 18-octabromo-meso-tetrakis(2-pyridyl)porphyrin, H 2 Br 8 T2PyP, is described, including the comparison of four attempted methods for the demetallation of ZnBr 8 T2PyP. One of the methods represents a strategy of demetallation based on the acid-base properties of the macrocycle, the solvent-dependent kinetics of metal insertion into porphyrins and the pH-dependent solubility of the 2-pyridylporphyrin derivatives in water. Self-coordinating aggregation of ZnBr 8 T2PyP in non-coordinating solvents was verified by 1 H NMR spectroscopy. The Mn(III)/Mn(II) redox potential for MnBr 8 T2PyPCl is 0.38 V higher than the reduction potential measured for its first-generation analogue, MnT2PyPCl. Cyclohexane hydroxylation by iodosylbenzene was performed in CH 3 CN catalyzed by MnBr 8 T2PyPCl and MnT2PyPCl. MnBr 8 T2PyPCl was highly active, even at low concentration (5 x 10 -5 M), but perhalogenation did not account for oxidative robustness. At such a low catalyst concentration, MnT2PyPCl exhibited no activity as inferred by comparison to blank experiments.

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Section: Catalytic Studiesmentioning

confidence: 87%

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

Rebouças

Carvalho

Idemori

2002

J. Porphyrins Phthalocyanines

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“…TFA > 99 %was purchased from Sigma-Aldrich Chemical Co. 5,10,15,20-Tetraphenylporphyrin, 5,10,15,20-tetra(4-pyridyl)porphyrin, 5,15-diphenylporphyrin, and 5,10,15-triphenylporphyrin were purchased from PorphyChem in Dijon, France. The b-pyrrole substituted free-base porphyrins in Scheme 1 [46,[51][52][53] and the free-base porphine in Scheme 2 [54,55] were synthesized by using literature procedures.…”

Section: Methodsmentioning

confidence: 99%

Tuning the Electrochemistry of Free‐Base Porphyrins in Acidic Nonaqueous Media: Influence of Solvent, Supporting Electrolyte, and Ring Substituents

et al. 2015

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International audienceA detailed study of reduction potentials, electroreduction mechanisms, and acid-base chemistry was carried out on two series of free-base porphyrins in nonaqueous media. The first series is represented by four -pyrrole-substituted tetraphenylporphyrin (TPP) derivatives, two of which are planar and two of which are nonplanar in their nonprotonated form. The second comprises porphyrins with 0-4 meso-phenyl groups on the macrocycle. Equilibrium constants for the conversion of each neutral porphyrin to its diprotic [H4P](2+) form were determined and the electrochemistry was then elucidated as a function of: 1)type of nonaqueous solvent, 2)anion of supporting electrolyte, 3)porphyrin ring substituents, and 4)concentration of acid added to solution. Spectroelectrochemistry was used to characterize absorption spectra of each electroreduced species and, when combined with results of the above studies, significantly improves our ability to tune redox reactivity of these types of compounds

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“…Such an approach was pioneered by Smith and co-workers who described the first electrosynthesis of porphyrins from a,c-biladienes. [24,25] More recently, an N-substituted cyclo [6]pyrrole was produced from a sterically constrained hexapyrrolylbenzene by using a covalently templated electrochemical procedure. [26] In the context of our own efforts to develop electrochemical oxidations as a potentially clean and straightforward complement to chemical-based oxidative procedures, we have reported the electrochemically driven ring-closure of a linear hexapyrrole to give a [24]hexaphyrin(1.0.1.0.0.0).…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Syntheses of Cyclo[n]pyrrole

Buda

Iordache

Bucher

et al. 2010

Chemistry A European J

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Cyclo[8]pyrrole was obtained efficiently when 3,3',4,4'-tetraethylbipyrrole was subjected to bulk electrolysis, with yields spanning a range from close to 0 % with tetra-n-butylammonium fluoride as the electrolyte, to almost 70 % when tetra-n-butylammonium hydrogensulfate was used for this purpose. These observations are consistent with the conclusion that the reaction is controlled by anion-related factors such as a specific templating effect. Note that cyclo[8]pyrrole was the only detectable macrocyclic product obtained from 3,3',4,4'-tetraethylbipyrrole under the conditions of the electrochemical oxidation. When similar electrolyses were performed by using 3,4-diethylpyrrole as the starting material, two products could be isolated, which were identified as being the cyclo[7]pyrrole and cyclo[8]pyrrole, respectively. Detailed analyses of the oxidized forms of cyclo[7]pyrrole and cyclo[8]pyrrole revealed that under the conditions of the electrolysis these latter species are not stable.

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Hoch‐ und perchlorierte meso‐Tetraphenylporphyrine

Abstract: Eine helicale Konformation und damit eine sterisch eher ungünstige Struktur kennzeichnet die Pentaketone 1 und 2. Aus einem einfachen Modell folgt, daß der strukturbestimmende Parameter die Minimierung des Gesamtdipolmoments ist.

Cited by 29 publications

References 11 publications

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

Perhalogenated 2-pyridylporphyrin complexes: synthesis, self-coordinating aggregation properties, and catalytic studies

Tuning the Electrochemistry of Free‐Base Porphyrins in Acidic Nonaqueous Media: Influence of Solvent, Supporting Electrolyte, and Ring Substituents

Electrochemical Syntheses of Cyclo[n]pyrrole

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