<i>Carbo</i>‐Quinoids: Stability and Reversible Redox‐Proaromatic Character towards <i>Carbo</i>‐Benzenes

Cocq, Kévin; Maraval, Valérie; Saffon‐Merceron, Nathalie; Saquet, Alix; Poidevin, Corentin; Lepetit, Christine; Chauvin, Rémi

doi:10.1002/anie.201407889

Cited by 17 publications

(16 citation statements)

References 22 publications

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“…[29] Finally,t he influence of the aromaticity of the central C 18 core on the enhancement of the TPAe fficiency deserves to be investigated in comparisonton onaromaticanalogues of 3a and 3b. [30] Experimental Section General THF and diethyl ether were dried and distilled over sodium/benzophenone, and pentane and dichloromethane over P 2 O 5 .A ll other reagents were used as commercially available. In particular,c ommercial solutions of nBuLi were 2.5 m in hexane, solutions of ethylmagnesium bromide were 3 m in THF,a nd solutions of HCl were 2 m in diethyl ether.P reviously described procedures were used for the preparation of pericyclynedione 4.…”

Section: Resultsmentioning

confidence: 99%

Difluorenyl carbo‐Benzenes: Synthesis, Electronic Structure, and Two‐Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores

Baglai

Anda-Villa

Barba-Barba

et al. 2015

Chemistry A European J

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The synthesis, crystal and electronic structures, and one- and two-photon absorption properties of two quadrupolar fluorenyl-substituted tetraphenyl carbo-benzenes are described. These all-hydrocarbon chromophores, differing in the nature of the linkers between the fluorenyl substituents and the carbo-benzene core (C-C bonds for 3 a, C-C=C-C expanders for 3 b), exhibit quasi-superimposable one-photon absorption (1PA) spectra but different two-photon absorption (2PA) cross-sections σ2PA. Z-scan measurements (under NIR femtosecond excitation) indeed showed that the C≡C expansion results in an approximately twofold increase in the σ2PA value, from 336 to 656 GM (1 GM = 10(-50) cm(4) s molecule(-1) photon(-1)) at λ = 800 nm. The first excited states of Au and Ag symmetry accounting for 1PA and 2PA, respectively, were calculated at the TDDFT level of theory and used for sum-over-state estimations of σ2PA(λi), in which λi = 2 hc/Ei, h is Planck's constant, c is the speed of light, and Ei is the energy of the 2PA-allowed transition. The calculated σ2PA values of 227 GM at 687 nm for 3 a and 349 GM at 708 nm for 3 b are in agreement with the Z-scan results.

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Section: Resultsmentioning

confidence: 99%

Difluorenyl carbo‐Benzenes: Synthesis, Electronic Structure, and Two‐Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores

Baglai

Anda-Villa

Barba-Barba

et al. 2015

Chemistry A European J

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“…The out-of-plane tensor component (NICS(1) zz ) is supposed to be an even more accurate index as it avoids the in-plane components. The aromatic character of carbobenzenes has been discussed in detail previously [52,53], in particular using the topological analysis of electron localization function (ELF) [54,55], or Schleyer's NICS indices [56,57]. Now, the analysis of the effect of guest insertion on the aromaticity of the carbo-benzene host ring is undertaken by the comparison of NICS(1) indices values mainly.…”

Section: Resultsmentioning

confidence: 99%

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

Turias

Poater²,

Chauvin

et al. 2015

Struct Chem

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The present computational study complements experimental efforts to describe and characterize carbo-benzene derivatives as paradigms of aromatic carbo-mers. A long-lasting issue has been the possibility of the π-electron crown of the C18 carbo-benzene ring to fit metals or any chemical agents in its core. A systematic screening of candidate inclusion complexes was carried out by density functional theory calculations. Mayer bond order, aromaticity indices, and energy decomposition analyses complete the understanding of the strength of the host-guest interaction. The change in steric and electronic properties induced by the guest agent is investigated by means of steric maps. Substitution of H atoms at the carbo-benzene periphery by electron-withdrawing or electron-donating groups is shown to have a determining influence on the stability of the inclusion complex ions: while electronegative substituents enhance the recognition of cations, electropositive substituents do the same for anions. The results confirm the experimental failure hitherto to evidence a carbo-benzene complex. Nevertheless, the affinity of carbo-benzene for the potassium cation appears promising for the design of planar hydrocarbon analogues of biologic ion carriersA.P. thanks the Spanish MINECO for a project CTQ2014-59832-JIN and European Commission for a Career Integration Grant (CIG09-GA-2011-293900

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“…5). 78 The non-expanded parent quinoid 23 could not be isolated because of the strong aromaticity of the corresponding C 6 benzene ring, 79 but the partly expanded C 14 representative 24 was described in a benzannelated form preventing aromatization (Fig. Beyond the quinone-hydroquinone system, it was thus illustrated for difluorenylidene-carbo-quinoid hydrocarbons 22.…”

Section: Proaromatic Carbo-quinoidsmentioning

confidence: 99%

“…redox transformation was finally evidenced by SnCl 2mediated reduction of 1y to 22a 78. The inset shows individual traces obtained with 1p (red) and control experiments without molecular conductor (black); (c) conductance vs. gating potential for 1p.…”

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“Carbo-aromaticity” and novel carbo-aromatic compounds

et al. 2015

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While the concept of aromaticity is being more and more precisely delineated, the category of "aromatic compounds" is being more and more expanded. This is illustrated by an introductory highlight of the various types of "aromaticity" previously invoked, and by a focus on the recently proposed "aromatic character" of the "two-membered rings" of the acetylene and butatriene molecules. This serves as a general foundation for the definition of "carbo-aromaticity", the relevance of which is surveyed through recent results in the synthetic, physical, and theoretical chemistry of carbo-mers and in particular macrocyclic-polycyclic representatives constituting a natural family of "novel aromatic compounds". With respect to their parent molecules, carbo-mers are constitutionally defined as "carbon-enriched", and can also be functionally regarded as "π-electron-enriched". This is exemplified by recent experimental and theoretical results on functional, aromatic, rigid, σ,π-macrocyclic carbo-benzene archetypes of various substitution patterns, with emphasis on the quadrupolar pattern. For the purpose of comparison, several types of non-aromatic references of carbo-benzenes are then considered, i.e. freely rotating σ,π-acyclic carbo-n-butadienes and flexible σ-cyclic, π-acyclic carbo-cyclohexadienes, and to "pro-aromatic" congeners, i.e. rigid σ,π-macrocyclic carbo-quinoids. It is shown that functional carbo-mers are entering the field of "molecular materials" for properties such as linear or nonlinear optical properties (e.g. dichromism and two-photon absorption) and single molecule conductivity. Since total or partial carbo-mers of aromatic carbon-allotropes of infinite size such as graphene (graphynes and graphdiynes) and graphite ("graphitynes") have long been addressed at the theoretical or conceptual level, recent predictive advances on the electrical, optical and mechanical properties of such carbo-materials are surveyed. Very preliminary experimental results on a carbo-benzenoid fragment are finally disclosed.

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Carbo‐Quinoids: Stability and Reversible Redox‐Proaromatic Character towards Carbo‐Benzenes

Cited by 17 publications

References 22 publications

Difluorenyl carbo‐Benzenes: Synthesis, Electronic Structure, and Two‐Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores

Difluorenyl carbo‐Benzenes: Synthesis, Electronic Structure, and Two‐Photon Absorption Properties of Hydrocarbon Quadrupolar Chromophores

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

“Carbo-aromaticity” and novel carbo-aromatic compounds

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