Porphyrins bearing quaternary pyridinium substituents

Śliwa, Wanda; Zujewska, T.; Mielniczak, Marian

doi:10.1007/bf00531536

Cited by 2 publications

(2 citation statements)

References 57 publications

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“…due to the presence of four electron-withdrawing viologen substituants. These results also stand in sharp contrast to previous studies demonstrating that the first two-electron reduction of the parent 5,10,15,20tetrakis(N-methyl pyridinyl)porphyrin (TPyPZn +4 ) derivatives is not centered on the peripheral pyridinium substituents but rather on the porphyrin ring to yield a porphyrin dianion (PP 2─ ) [49][50][51][52][53][54]. Such fundamental differences observed within a series of structurally related viologen-or-pyridinium-appended porphyrin compounds can actually be attributed to the much better electron-acceptor properties of the viologen units, which therefore end-up being reduced before the porphyrin unit.…”

Section: Electrochemistry In Organic Mediumcontrasting

confidence: 99%

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Chowdhury

Nassar

Guy

et al. 2019

Electrochimica Acta

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The present paper reports on the formation and on the electrochemical/spectroscopic characterization of inclusion complexes formed in aqueous media between cucurbit[7 or 8]urils cavitands (CB[7], CB[8]) and a rigid four-pointed star-shaped viologen-appended porphyrin tecton. The formation of discrete 4:1 pseudo-rotaxane-like caviplexes, involving threading of CB[n] rings on the rigid viologen-based star's branches has been demonstrated by nuclear magnetic resonance and mass spectrometry measurements. Then, the photo-and redoxtriggered formation of 2D supramolecular assemblies involving CB[8]s and the four electron reduced tectons as key building elements, has been established on the ground of in-depth electrochemical and spectroscopic analyses supported by quantum calculations. The CB[8]promoted intermolecular -dimerization of the viologen cation radicals introduced at the meso positions of the porphyrin plateform has been brought to light through the diagnostic signatures of the 1:2 host-guest ternary caviplexes formed between viologen and CB[8] and by spectroscopic data collected after electrochemical, chemical or photochemical reduction of the viologen-based tectons. The CB[8] hosts not only proved useful to promote the redox-triggeredformation of supramolecular assemblies, it was also found to prevent the chemical reduction of the porphyrin ring in aqueous media and its subsequent conversion into phlorin products.

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Section: Electrochemistry In Organic Mediumcontrasting

confidence: 99%

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Chowdhury

Nassar

Guy

et al. 2019

Electrochimica Acta

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“…Heterocyclic and alkyl groups are of interest for biomedical applications and for studies in supramolecular chemistry. In this regard, porphyrins bearing pyridyl groups have been used for DNA intercalation, – DNA cleavage, , DNA labeling, telomerase or acetylcholinesterase inhibition, prion binding, superoxide dismutase mimicry, photodynamic inactivation, , radiosensitization, binding to nanoparticles, and assembly into micelles, bilayer lipid membranes, molecular squares, arrays, oligomers, , and light-harvesting architectures . Several examples have been reported of porphyrins that bear both pyridyl and alkyl groups. ,,– Most of the porphyrins bearing fewer than four identical pyridyl groups have been formed by statistical reactions, which give multiple products.…”

Section: Introductionmentioning

confidence: 99%

Rational or Statistical Routes from 1-Acyldipyrromethanes to meso-Substituted Porphyrins. Distinct Patterns, Multiple Pyridyl Substituents, and Amphipathic Architectures

2008

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New methodology is described for the synthesis of porphyrins bearing four (A 4, cis-A 2B 2, cis-ABC 2, trans-A 2B 2) or fewer (A, cis-AB, cis-A 2, trans-A 2) meso substituents. The method entails condensation of two 1-acyldipyrromethanes in the presence of a metal salt (MgBr 2, 3 mol equiv) and a noncoordinating base (DBU, 10 mol equiv) in a noncoordinating solvent (toluene) with heating (conventional or microwave irradiation) and exposure to air. The rational synthesis of trans-A 2B 2- or trans-A 2-porphyrins was achieved via condensation of two identical 1-acyldipyrromethanes. The statistical synthesis of various meso-substituted porphyrins was achieved via condensation of two nonidentical 1-acyldipyrromethanes. Both routes possess attractive features including (1) no scrambling, (2) good yield (up to 60%) at high concentration (100 mM) for the macrocycle-forming step, (3) reasonable scope (aryl, heteroaryl, alkyl, or no substituent), (4) short reaction time ( approximately 2 h) via microwave irradiation, (5) magnesium porphyrins as the products, which easily undergo demetalation, and (6) facile chromatographic purification. A key advantage of the statistical route is to obtain a cis-substituted porphyrin without the corresponding trans isomer. For example, reaction of an A/B-substituted 1-acyldipyrromethane and the fully unsubstituted 1-formyldipyrromethane gave the magnesium chelates of three porphyrins: the trans-A 2B 2-porphyrin, the "hybrid" cis-AB-porphyrin, and porphine (no trans-AB-porphyrin can form), which were readily demetalated and separated as the free base species. Altogether 26 1-acyldipyrromethanes and 26 target porphyrins have been prepared, including many with two different pyridyl substituents. One set of amphipathic porphyrins includes cis-A 2B 2- or cis-A 2BC-porphyrins wherein A = pentyl and B/C = pyridyl ( o-, m-, p-). Taken together, the rational and statistical routes enable facile conversion of readily available 1-acyldipyrromethanes to diverse porphyrins bearing 1-4 meso substituents for which access is limited via other methods.

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Porphyrins bearing quaternary pyridinium substituents

Cited by 2 publications

References 57 publications

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Photo/redox-responsive 2D-Supramolecular assembly involving Cucurbit[8]uril and a star-shaped porphyrin tecton

Rational or Statistical Routes from 1-Acyldipyrromethanes to meso-Substituted Porphyrins. Distinct Patterns, Multiple Pyridyl Substituents, and Amphipathic Architectures

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