A Porphyrin with a C═C Unit at Its Center

Vaid, Thomas P.

doi:10.1021/ja205738z

Cited by 69 publications

(65 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The spectrum exhibited a sharp singlet signal for the β protons at δ =4.99 ppm (Figure c), which were, compared to 1 , considerably upfield shifted. Comparison of the chemical shifts of selected isophlorins with antiaromatic and nonaromatic characters, other relevant antiaromatic porphyrinoids, and quinoidal thiophene compounds is summarized in Table S16. The peak of [ 2 ] 2− is shifted downfield compared to those of the strong antiaromatic analogues (from 3 to −1 ppm), but shifted upfield compared to those of the distorted nonaromatic analogues and quinoidal thiophene compounds (from 8 to 6 ppm).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Facile Redox‐Induced Aromatic–Antiaromatic Interconversion of a β‐Tetracyano‐21,23‐Dithiaporphyrin under Ambient Conditions

Yamashita

Nakajima

Honda

et al. 2020

Chemistry A European J

View full text Add to dashboard Cite

Facile redox‐induced aromatic–antiaromatic interconversions were accomplished by using β‐tetracyano‐21,23‐dithiaporphyrin (CN4S2Por). Introduced cyano groups not only increased the reduction potential of the porphyrin core but also stabilized the antiaromatic isophlorin (CN4S2Iph) by π conjugation. The reduction of CN4S2Por with hydrazine in polar solvents quantitatively affords CN4S2Iph, even under ambient conditions. CN4S2Iph retains a nearly planar conformation and exhibits considerable antiaromaticity. Aerobic oxidation of CN4S2Iph to CN4S2Por occurs in nonpolar solvents. This study was conducted to contribute to the understanding of the structure–antiaromaticity relationship.

show abstract

Section: Resultsmentioning

confidence: 99%

“…The second type of isophlorins contain tetravalent elements, such as Si or Ge or their respective analogues . They complement isophlorins in terms of their charge valance because isophlorins serve as tetravalent ligands.…”

Section: Introductionmentioning

confidence: 99%

Facile Redox‐Induced Aromatic–Antiaromatic Interconversion of a β‐Tetracyano‐21,23‐Dithiaporphyrin under Ambient Conditions

Yamashita

Nakajima

Honda

et al. 2020

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…5 Recently, a number of organic electron donors have 15 been synthesized that are very strong reducing agents (1)(2)(3)(4)(5)(6)(7)(8). All of these compounds critically contain nitrogen atoms that are capable of stabilizing both positive charge and radical character, as the donors undergo oxidation.…”

mentioning

confidence: 99%

“…7 Neither 1 nor its oxidized products is aromatic. Compound 2 could be considered anti-aromatic 8 if planar and so its oxidation through loss of two electrons might 30 expect to be strongly driven; however it is quite deformed from planarity and it contains two aromatic pyrrole rings -as a result it is not a strong reducing agent. Compound 3 9 is already aromatic and hence its oxidation does not benefit from aromatization as a driving force, and so it also is not a strong donor of electrons.…”

mentioning

confidence: 99%

A novel neutral organic electron donor with record half-wave potential

2013

View full text Add to dashboard Cite

This version is available at https://strathprints.strath.ac.uk/46029/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.Journal Name of one and two electrons respectively, also plays an important role in determining the strength of these electron donors. Table 1 compares the oxidation potentials of these compounds with the widely used sulfur-containing electron donor, tetrathiafulvalene (TTF).Among the nitrogen-containing electron-donors, TDAE (1) is the parent compound in the series and the standard by which the others can be judged. 7 Neither 1 nor its oxidized products is aromatic. Compound 2 could be considered anti-aromatic 8 if planar and so its oxidation through loss of two electrons might 30 expect to be strongly driven; however it is quite deformed from planarity and it contains two aromatic pyrrole rings -as a result it is not a strong reducing agent. Compound 3 9 is already aromatic and hence its oxidation does not benefit from aromatization as a driving force, and so it also is not a strong donor of electrons. In 35 contrast, donors 4-8 are all converted into aromatic products upon oxidation [10][11][12][13][14][15][16][17][18][19] and this adds to their strength as reducing agents. To illustrate the aromaticity that arises, the oxidation products of compound 8 are also shown in Figure 1. Loss of one electron leads to radical cation 13 featuring one pyridinium ring, 40 while loss of a second electron affords the aromatic disalt 14. In terms of the applications of these stronger electron donors, benzimidazole-derived 6 converts iodoarenes into aryl radicals, 15 while the stronger donors 7 and 8 reduce the same substrates to aryl anions.12,14 Donors 7 and 8 are also able to reduce 45 arenesulfonamides, 16 Weinreb amides 17 and acyloin derivatives. reducing power is significantly less than that of the strongest metals (e.g. the oxidation potential of Li, E 0 = 3.02 V) 20 and questions arise about whether a limit is bei...

show abstract

“…In general, two‐electron‐ and one‐electron‐reduced porphyrins (20π and 19π porphyrins, respectively) are extremely unstable under atmospheric conditions because of their high‐energy highest occupied molecular orbital (HOMO) and singly occupied molecular orbital (SOMO), respectively . Several approaches have been proposed to isolate 20π and 19π porphyrins in neutral forms, which basically rely on the concept of lowering the HOMO or SOMO energy levels . However, most of the reported neutral 20π and 19π porphyrins are highly distorted and/or still air‐sensitive.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of redox‐switchable zinc complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin

Sudoh

Furukawa

Nakano

et al. 2018

Heteroatom Chemistry

View full text Add to dashboard Cite

The synthesis, aromaticity, and optical and electrochemical properties of zinc(II) complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin (TriAAOP) were investigated. Metal‐templated cyclization of a zinc(II) 1,19‐dichloro‐5,10,15‐triaryl‐10‐azatetrapyrrin complex with an oxygen source afforded 20π TriAAOP in the neutral form. Oxidation of 20π TriAAOP with silver (I) hexafluorophosphate generated the 19π radical cation or 18π dication depending on the content of oxidant used. The interconversion between the three oxidation states (18π, 19π, and 20π) resulted in distinct changes in the aromaticity and optical properties of the 15‐aza‐5‐oxaporphyrin π‐system. Nuclear magnetic resonance spectroscopy of 20π TriAAOP revealed its antiaromatic character, whereas that of the 18π TriAAOP dication showed its aromatic character. The combined effect of the two meso‐heteroatoms was directly reflected in the redox properties of the porphyrin ring; TriAAOP was reduced more easily and more difficult to oxidize than the zinc(II) complex of 5,10,15,20‐tetraaryl‐5,15‐diaz‐aporphyrin (TADAP). In the ultraviolet‐visible‐near–infrared spectra of the materials, the lowest‐energy electronic excitations of the 19π and 18π TriAAOP derivatives were considerably red‐shifted compared with those of the isoelectronic TADAP derivatives. Based on the results of density functional theory calculations, it was concluded that the observed differences between TriAAOP and TADAP would arise from the high electronegativity of oxygen; specific frontier orbitals of the TriAAOP π‐systems were energetically stabilized relative to those of the TADAP π‐system. The present findings corroborate that the meso‐modification of a porphyrin rings with different kinds of heteroatoms is a promising strategy to fine tune their light‐response properties that are switchable by reversible single electron transfer processes.

show abstract

A Porphyrin with a C═C Unit at Its Center

Cited by 69 publications

References 52 publications

Facile Redox‐Induced Aromatic–Antiaromatic Interconversion of a β‐Tetracyano‐21,23‐Dithiaporphyrin under Ambient Conditions

Facile Redox‐Induced Aromatic–Antiaromatic Interconversion of a β‐Tetracyano‐21,23‐Dithiaporphyrin under Ambient Conditions

A novel neutral organic electron donor with record half-wave potential

Synthesis and properties of redox‐switchable zinc complexes of 10,15,20‐triaryl‐15‐aza‐5‐oxaporphyrin

Contact Info

Product

Resources

About