Mixed-valence, conjugated semiquinones

Jozefiak, Thomas H.; Almlöf, Jan; Feyereisen, Martin W.; Miller, Larry L.

doi:10.1021/ja00193a054

Cited by 47 publications

(31 citation statements)

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“…[58] In this way, highly functionalised dyes can easily be built up from substituted tolanes. We started from bis{4-[N,N-di-(4-methoxyphenyl)amino]phenyl}acetylene (2) which trimerised in the presence of [Co 2 (CO) 8 ] catalyst to afford the symmetrical hexakis{4-[N,N-di(4-methoxyphenyl)amino]phe-nyl}benzene (3) in 60 % yield (Scheme 1); properties of 3 were preliminarily reported elsewhere. [21] The para positions of the phenylamine groups were protected to guarantee reversible redox behaviour.…”

Section: Resultsmentioning

confidence: 99%

“…This DG 0 shift can be estimated by the shift of the IV-CT band energy of 2 versus 4 in CH 2 Cl 2 which is 290 cm À1 . [59] [Co 2 (CO) 8 ]-catalysed trimerisation of 4 gave two regioisomers 5 and 6 in 20 % and 60 % yield, respectively, which could be separated by flash chromatography (Scheme 2). The ratio of yields corresponds exactly to the statistical (1:3) formation of the 1,3,5 and 1,2,4 isomers.…”

Section: Resultsmentioning

confidence: 99%

“…Ground state potential energy surface of 5 3 from the minimum energy solution of Equation(8). The ET coordinates refer to Scheme 8.…”

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confidence: 99%

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Optically and Thermally Induced Electron Transfer Pathways in Hexakis[4-(N,N-diarylamino)phenyl]benzene Derivatives

Lambert¹,

Nöll²

2002

Chem. Eur. J.

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The optically and thermally induced electron transfer pathways of highly symmetrical (D3) hexaarylbenzene systems with six triarylamine redox sites have been investigated. Owing to slightly different local redox potentials, the radical trication could be selectively generated by electrochemical methods. This trication shows a strong intervalence charge‐transfer band in the near infrared (NIR) that was measured by spectroelectrochemistry and analysed using multi‐dimensional Mulliken–Hush theory. Quantum chemical AM1 CI calculations indicate that there is no optically induced concerted three‐electron transfer that transforms the ground state into a state in which all three positively charged triarylamine moieties change place with their neutral neighbours. The potential energy surface of the ground state was constructed by using quadratic potentials. From this potential surface it is apparent that there is also no thermally allowed concerted three‐electron transfer pathway. Instead, three consecutive one‐electron transfer steps are necessary for this process.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Optically and Thermally Induced Electron Transfer Pathways in Hexakis[4-(N,N-diarylamino)phenyl]benzene Derivatives

Lambert¹,

Nöll²

2002

Chem. Eur. J.

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“…39,87 Much of this research focused on the question, at what distance between the two redox active units would a transition occur from a fully delocalized class III structure (as observed for 12 À ) to a charge-localized class II system? For the diquinones, this turned out to be the case already for the naphthalene-bridged system 13 À .…”

Section: Distance Dependencementioning

confidence: 99%

Organic Mixed Valence

2011

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“…triarylamines, [5][6][7][8][9][10] perchlorotriphenylmethyl radicals, [11][12][13] hydrazines, 14,15 dimethoxybenzenes, 16,17 or quinones. 18,19 ET may proceed between the redox centers via the bridge, thermally or optically induced. The optical ET is associated with the so-called intervalence charge transfer (IV-CT) band which usually appears in the NIR.…”

Section: Introductionmentioning

confidence: 99%

Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?

Kaupp

Renz

Parthey

et al. 2011

Phys. Chem. Chem. Phys.

128

157

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This article discusses recent progress by a combination of spectroscopy and quantum-chemical calculations in classifying and characterizing organic mixed-valence systems in terms of their localized vs. delocalized character. A recently developed quantum-chemical protocol based on non-standard hybrid functionals and continuum solvent models is evaluated for an extended set of mixed-valence bis-triarylamine radical cations, augmented by unsymmetrical neutral triarylamine-perchlorotriphenylmethyl radicals. It turns out that the protocol is able to provide a successful assignment to class II or class III Robin-Day behavior and gives quite accurate ground-and excited-state properties for the radical cations. The limits of the protocol are probed by the anthracene-bridged system 8, where it is suspected that specific solute-solvent interactions are important and not covered by the continuum solvent model. Intervalence charge-transfer excitation energies for the neutral unsymmetrical radicals are systematically overestimated, but dipole moments and a number of other properties are obtained accurately by the protocol.

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Mixed-valence, conjugated semiquinones

Cited by 47 publications

References 1 publication

Optically and Thermally Induced Electron Transfer Pathways in Hexakis[4-(N,N-diarylamino)phenyl]benzene Derivatives

Optically and Thermally Induced Electron Transfer Pathways in Hexakis[4-(N,N-diarylamino)phenyl]benzene Derivatives

Organic Mixed Valence

Computational and spectroscopic studies of organic mixed-valence compounds: where is the charge?

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