Non-kekulé molecules derived conceptually by heteroatom-for-carbon substitution in alternant hydrocarbons

Rule, Mark; Matlin, Albert R.; Seeger, David E.; Hilinski, Ε. F.; Dougherty, Dennis A.; Berson, Jerome A.

doi:10.1016/0040-4020(82)80159-2

Cited by 51 publications

(20 citation statements)

References 31 publications

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“…The meta-benzoquinodimethane diradical has an S = 1 ground state. [408][409][410] This is consistent with its electronic structure showing two singly occupied degenerate, orthogonal and coextensive orbitals (orbitals 4 and 5 in Fig. 33).…”

Section: Generalitiessupporting

confidence: 85%

Polymers for electronics and spintronics

et al. 2013

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This critical review is devoted to semiconducting and high spin polymers which are of great scientific interest in view of further development of the organic electronics and the emerging organic spintronic fields. Diversified synthetic strategies are discussed in detail leading to high molecular mass compounds showing appropriate redox (ionization potential (IP), electron affinity (EA)), electronic (charge carrier mobility, conductivity), optoelectronic (electroluminescence, photoconductivity) and magnetic (magnetization, ferromagnetic spin interactions) properties and used as active components of devices such as n- and p-channel field effect transistors, ambipolar light emitting transistors, light emitting diodes, photovoltaic cells, photodiodes, magnetic photoswitches, etc. Solution processing procedures developed with the goal of depositing highly ordered and oriented films of these polymers are also described. This is completed by the description of principal methods that are used for characterizing these macromolecular compounds both in solution and in the solid state. These involve various spectroscopic methods (UV-vis-NIR, UPS, pulse EPR), electrochemistry and spectroelectrochemistry, magnetic measurements (SQUID), and structural and morphological investigations (X-ray diffraction, STM, AFM). Finally, four classes of polymers are discussed in detail with special emphasis on the results obtained in the past three years: (i) high IP, (ii) high |EA|, (iii) low band gap and (iv) high spin ones.

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Section: Generalitiessupporting

confidence: 85%

Polymers for electronics and spintronics

et al. 2013

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“…Heterospin diradicals are important probes of the interplay between frontier orbital energy level perturbation by substitution, versus the parity-based tendencies of such systems to give high-spin ground-state multiplicities. In an archetypal example, m -benzoquinomethane, 1 , has been experimentally shown to have a triplet ground state (or possibly a near-degeneracy of triplet and singlet states) . Recent multiconfiguration self-consistent field computations are in agreement with the experiment, and show a favoring of the triplet over the singlet state by about 10 kcal/mol .…”

Section: Introductionmentioning

confidence: 77%

3,5-Di-tert-butyl-3‘-(N-tert-butyl-N-aminoxy)-4-oxybiphenyl: A Heterospin Diradical with Temperature Dependent Behavior

et al. 1999

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The title diradical was synthesized and investigated by ESR and UV−vis spectroscopy. It was found to have a lifetime of weeks even in the presence of oxygen, and even survives brief heating in toluene up to about 60 °C. In the UV−vis spectrum, the diradical showed reversible thermochromic behavior in the −10 to 50 °C range. In the ESR spectrum, hyperfine analysis showed nearly isolated behavior by the phenoxyl and nitroxide spin carrying units. Upon warming, additional, broad lines appeared at the expense of the lower temperature lines. This temperature behavior was reversible over the 0 to 50 °C range, so long as the raised temperatures were not maintained for long time periods. The spectral behavior is interpreted as being due to temperature-dependent conformational effects on the exchange coupling between the spin carrying units, i.e., J-modulated exchange behavior.

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“…Parent 1,3-benzoquinone methide (10) and 1,3-naphthoquinone methide (11) have been prepared from unambiguous precursors by Berson and co-workers. 38 Both diradicals gave rise to persistent EPR signals, which were characteristic for randomly oriented molecules in a triplet spin state: |D/hc| = 0.0266, |E/hc| = 0.0074 cm Ϫ1 for 10 (decay above 40 K), and |D/hc| = 0.0204, |E/hc| = 0.0052 cm Ϫ1 for 11 (linear Curie plot 15-84 K, curvature below 15 K was attributed to saturation). The temperature dependence of the EPR signal intensities indi-cated that the triplet state is the ground state of both 10 and 11, but stereochemical studies suggested that a thermally accessible singlet state is the reactive entity in cycloaddition reactions of 10.…”

Section: Previous Work On 13-quinone Methidesmentioning

confidence: 98%

Primary photoreactions of phylloquinone (vitamin K1) and plastoquinone-1 in solution

Hangarter

Hörmann

Kamdzhilov

et al. 2003

Photochem Photobiol Sci

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The photoreactions of electron transport quinones vitamin K1 (1) and plastoquinone-1 (2) were studied by picosecond pump-probe spectroscopy, nanosecond flash photolysis, step-scan FTIR spectroscopy, and by irradiation in glassy solvents at 77 K with optical and EPR detection. In polar solvents, charge transfer from the beta,gamma-double bond to the quinone moiety initiates intramolecular proton transfer from the side chain, k = 2.7 x 10(11) s-1, yielding 1,3-quinone methide diradicals, which establish a metastable equilibrium between the singlet and the triplet state. Subsequent proton transfer through the solvent forms 1,2-quinone methides. In apolar solvents the predominant primary photoreaction is formation of cyclic 'preoxetane' diradicals (kform > 3 x 10(11) s-1, kdecay approximately 1 x 10(9) s-1), which revert to a photostationary E/Z mixture of the starting materials, unless they are trapped by oxygen. The beta,gamma-double bond in the isoprenoid side chain thus provides two efficient deactivation processes, which prevent the intermolecular photoreactions commonly observed with the parent quinones. A combined mechanistic scheme rationalizes the known photoreactions of 1, 2 and related compounds in solution.

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Non-kekulé molecules derived conceptually by heteroatom-for-carbon substitution in alternant hydrocarbons

Cited by 51 publications

References 31 publications

Polymers for electronics and spintronics

Polymers for electronics and spintronics

3,5-Di-tert-butyl-3‘-(N-tert-butyl-N-aminoxy)-4-oxybiphenyl: A Heterospin Diradical with Temperature Dependent Behavior

Primary photoreactions of phylloquinone (vitamin K1) and plastoquinone-1 in solution

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