E.S.R. study of 12,12c-dihydro-4,4,8,8,12,12-hexamethyl-4H, 8H-dibenzo [cd,mn] pyren-12c-yl, a planar triphenylmethyl.

Neugebauer, Franz A.; Hellwinkel, Dieter; Aulmich, Gerhard

doi:10.1016/s0040-4039(01)85757-9

Cited by 23 publications

(19 citation statements)

References 17 publications

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“…Each radical showed fairly reversible oxidation and reduction waves with an arrow electrochemical gap (0.59 eV for both radicals). Spin-density distributions calculated at the UB3LYP/6-31G(d) level [12] also show extensive spin delocalization over the whole fused p-network (Figure 3d,e), as attributed to the rigidly held planar structures with perpen-dicular porbitals.Similar spin delocalization was reported for other planar organic radicals, [17] which were not as stable as 7Ni and 7FB,t hus underlining the effective radical-stabilization ability of porphyrins.…”

Section: Angewandte Chemiesupporting

confidence: 75%

Spontaneous Formation of an Air‐Stable Radical upon the Direct Fusion of Diphenylmethane to a Triarylporphyrin

Kato

Cha

et al. 2016

Angew Chem Int Ed

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The direct fusion of a diphenylmethane segment to a Ni(II) 5,10,15-triarylporphyrin with three linkages furnished an air- and moisture-stable neutral radical through unexpected and spontaneous oxidation. This radical was demetalated by treatment with H2 SO4 and CF3 CO2 H to provide the corresponding free-base radical. These porphyrin radicals are very stable owing to spin delocalization and have been fully characterized through UV/Vis/NIR absorption spectroscopy, X-ray crystallographic analysis, magnetic susceptibility measurements, electrochemical studies, laser-based ultrafast spectroscopic studies, and theoretical calculations. They were chemically oxidized and reduced to the corresponding cation and anion but did not react with hydrogen-atom donors.

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Section: Angewandte Chemiesupporting

confidence: 75%

Spontaneous Formation of an Air‐Stable Radical upon the Direct Fusion of Diphenylmethane to a Triarylporphyrin

Kato

Cha

et al. 2016

Angew Chem Int Ed

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“…To the best of our knowledge, only ve examples of [4]helicene carbon-centered radicals have been reported. [32][33][34][35][36] Of these radicals, two showed limited stability and two were formed by bulk electrolysis, and no crystal structures were reported (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

“…34 Later, Aulmich and co-workers synthesized a [4]helicene radical (II) with dimethyl-methylene units as bridging groups. 32,36 These two radicals showed low stability, readily decomposing when exposed to air, and no electronic structures were reported for them. More recently, Laursen et al generated a quinolinoacridinium [4]helicene radical (III) by in situ electrochemical reduction of N,N 0 -dialkyl-1,13-dimethoxyquinacridinium (DMQA + ) and studied it by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies.…”

Section: Introductionmentioning

confidence: 99%

Persistent, highly localized, and tunable [4]helicene radicals

et al. 2020

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“…Since Martin and Smith13 described the synthesis of the trioxatriangulenium ion (TOTA + ) in 1964, this compound has been the subject of some attention due to its properties as a stable carbenium ion14–18 and in the radical and dimeric states 19–22. In recent years, the triangulene skeleton has been used in the construction of macrocyclophanes23–25 and in stable triplet π biradicals 26, 27.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure, and Properties of Azatriangulenium Salts

2001

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A general synthetic route to novel nitrogen-bridged heterocyclic carbenium ions of the acridinium and triangulenium type has been developed and investigated. The synthetic method is based on nucleophilic aromatic substitution (SNAr) on the tris(2,6-dimethoxyphenyl)carbenium ion (1) with primary amines and, by virtue of its stepwise and irreversible nature, provides a powerful tool for the preparation of a wide variety of new heterocyclic carbenium salts. Several derivatives of the three new oxygen- and/or nitrogen-bridged triangulenium salts, azadioxa- (6), diazaoxa- (7), and triazatriangulenium (4), have been synthesized and their physicochemical properties have been investigated. Crystal structures for compounds 2 b-PF6, 2 d-PF6, 4b-BF4, 4c-BF4, 6e-BF4, and 8 are reported. The different packing modes found for the triazatriagulenium salts are discussed in relation to the electrostatic and space-filling requirements of the ions. The stabilities of the cations 6a, 7b, and 4a, as expressed by their pKR+ values, have been determined in strongly basic nonaqueous solution by use of the C_ acidity function; the values obtained were 14.5, 19.4, and 23.7, respectively. This study further implied that the C_ scale in its present form is unsuitable for the precise determination of pKR+ values beyond 22.

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E.S.R. study of 12,12c-dihydro-4,4,8,8,12,12-hexamethyl-4H, 8H-dibenzo [cd,mn] pyren-12c-yl, a planar triphenylmethyl.

Cited by 23 publications

References 17 publications

Spontaneous Formation of an Air‐Stable Radical upon the Direct Fusion of Diphenylmethane to a Triarylporphyrin

Spontaneous Formation of an Air‐Stable Radical upon the Direct Fusion of Diphenylmethane to a Triarylporphyrin

Persistent, highly localized, and tunable [4]helicene radicals

Synthesis, Structure, and Properties of Azatriangulenium Salts

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