Polycyclen vom triangulentyp

Hellwinkel, Dieter; Melan, Michael; Aulmich, Gerhard

doi:10.1016/s0040-4039(00)74615-6

Cited by 9 publications

(6 citation statements)

References 4 publications

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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%

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

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Along this line,planar triphenylmethyl derivatives (39 a-c)w ere synthesized in early studies utilizing oxo-or dimethylmethylene bridges ( Figure 6). [58] Unfortunately, these radicals were not very stable toward oxygen, in contrast to successes in sterics at the ortho-positions.I n2 016, Osuka and co-workers examined direct fusion of diphenylmethane to ameso-arylporphyrin under C À Hactivating conditions and the obtained radical 40Ni by hydrogen-atom release. [59] The radical was viewed as ac oplanarized diphenyl(porphyrinyl)methyl and was entirely unreactive to either air, water, silica gel, or hydrogen-atom donors such as nBu 3 SnH and ascorbic acid.…”

Section: Radicals Based On Fused P-skeletonsmentioning

confidence: 99%

Platforms for Stable Carbon‐Centered Radicals

2019

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Organic radicals can potentially play important roles in functional materials owing to an unpaired electron, but they are usually highly reactive and difficult to use. Therefore, stabilization of organic radicals is important. Among organic radicals, carbon‐centered radicals are promising because of their trivalent nature, which enables structural diversity and elaborate designs, but they are also less stable because of the reactivities towards carbon–carbon bond formation and atmospheric oxygen. Recently, stable carbon‐centered radicals across diverse molecular platforms have been increasingly explored. This Minireview highlights these newly explored, stable carbon‐centered radicals, with a focus on porphyrinoid‐stabilized radicals because of their remarkable spin delocalization abilities.

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“…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). In 1958, Neunhoffer and Haase reported the first [4]helicene radical, the doubly ortho-bridged radical (I) (see Scheme 1).…”

Section: Scheme 1 Literature Reports and This Work On [4]helicene Radicalmentioning

confidence: 99%

Section: Scheme 1 Literature Reports and This Work On [4]helicene Radicalmentioning

confidence: 99%

Persistent, Highly Localized, and Tunable [4]Helicene Radicals

Shaikh

Moutet

Veleta

et al. 2020

Preprint

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<p><a>Persistent organic radicals have gained considerable attention in the </a>fields of catalysis and material sciences. In particular, helical molecules are of great interest for the development and application of novel organic radicals in optoelectronic and spintronic materials. Here we report the syntheses of easily tunable and stable neutral quinolinoacridine radicals under anaerobic conditions by chemical reduction of their quinolinoacridinium cation analogs. The structures of these [4]helicene radicals were determined by X-ray crystallography. Density functional theory (DFT) calculations, supported by Electron paramagnetic resonance (EPR) measurements, indicate that over 40% of spin density is located at the central carbon of the [4]helicene radicals regardless of their structural modifications. The localization of the charge promotes a reversible oxidation to the cation upon exposure to air. This unusual reactivity toward molecular oxygen was monitored via UV-Vis spectroscopy.</p>

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Polycyclen vom triangulentyp

Cited by 9 publications

References 4 publications

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

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

Platforms for Stable Carbon‐Centered Radicals

Persistent, Highly Localized, and Tunable [4]Helicene Radicals

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