Dimerization of organic free radicals in solution.

Grampp, Günter; Landgraf, Stephan; Rasmussen, Kenneth; Strauß, Stefan

doi:10.1016/s1386-1425(01)00712-0

Cited by 26 publications

(28 citation statements)

References 26 publications

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“…From the slope of this plot, while taking r = r = 3.11 Å, the reaction distance becomes ' = 5.0 Å, which is in reasonably good agreement with the value of ' = 5.4 Å found in the theoretical calculations [94]. The experimental value of ' corresponds to KA = 0.21 l mol -1 .…”

Section: Methodssupporting

confidence: 87%

“…The reported results have dealt with the self-exchange of various nitroxide couples in acetonitrile [93] as well as of that of TEMPO with its oxidized counterpart in several different solvents [94]. For the latter couple, the temperature dependence of the exchange reaction has also been investigated [95].…”

Section: Methodsmentioning

confidence: 99%

“…The experimental results of references [94] and [95] serve as a good example of how ESR line broadening experiments can be utilized to study solvent effects on electron transfer. Numbers in brackets correspond to the relevant reference.…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

ESR Spectroscopy of Nitroxides: Kinetics and Dynamics of Exchange Reactins

Grampp¹,

Rasmussen²

2012

Nitroxides - Theory, Experiment and Applications

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Section: Methodssupporting

confidence: 87%

Section: Methodsmentioning

confidence: 99%

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ESR Spectroscopy of Nitroxides: Kinetics and Dynamics of Exchange Reactins

Grampp¹,

Rasmussen²

2012

Nitroxides - Theory, Experiment and Applications

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“…It is widely used as an EPR standard and serves as a radical scavenger/antioxidant, and, as such, it has numerous biological applications. 3,4 Since its discovery by G. Coppinger, 1 galvinoxyl and many of its derivatives have been studied extensively and electronic absorption, 5 photoelectron, 6 temperature dependent EPR spectra, 5,7,8 magnetic properties, 5,9,10 X-ray structure, 11,12 and photolysis experiments 13,14 have been published. Galvinoxyl has a C 2 rotational symmetry axis in crystals.…”

Section: Introductionmentioning

confidence: 99%

Photophysics of the galvinoxyl free radical revisited

Grilj

Zonca

Daku

et al. 2012

Phys. Chem. Chem. Phys.

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The photophysical properties of the free neutral radical galvinoxyl were studied by a combination of femtosecond time-resolved spectroscopy and quantum chemical calculations. The electronic absorption spectrum is dominated by an intense band at 430 nm that is ascribed to the D 9,10 ' D 0 transitions. Upon photoexcitation at 400 nm, the population of the D 9,10 states decays within less than 200 fs to the electronic ground state. This ultrafast internal conversion does not involve intramolecular modes with large amplitude motion as the measured dynamics does not show any significant dependence on the environment, but is most probably facilitated by a high density of electronic states of different character. Depending on the solvent, a weak transient band due to the galvinoxylate anion is also observed. This closed-shell species, which is fluorescent although its deactivation is also dominated by non-radiative decay, is generated upon biphotonic ionization of the solvent and electron capture. The ultrashort excited-state lifetime of the galvinoxyl radical precludes photoinduced disproportionation previously claimed to be at the origin of the formation of both anion and cation.

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“…A dimerization energy of −51 kJ/ mol is reported. 39 It is probable that intermolecular forces lead to dimerization effects already in solution. This is consistent with results on gavinoxyl crystals, 25 where all structures rely mainly on the interaction between the carbon rings.…”

Section: A Topography: Stm Resultsmentioning

confidence: 99%

Galvinoxyl monolayers on Au(111) studied by STM, EPR, and cyclic voltammetry

et al. 2006

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Galvinoxyl layers on Au͑111͒ have been studied by scanning tunnelling microscopy ͑STM͒, electron paramagnetic resonance ͑EPR͒, and cyclic voltammetry ͑CV͒. We observe two phases: configuration I having a molecular density of 1.57± 0.16ϫ 10 −10 mol/ cm 2 and a rectangular lattice ͑15 Å by 7 Å͒ observed at room temperature and down to 140 K; configuration II with a slightly smaller molecular density of 1.37± 0.14 ϫ 10 −10 mol/ cm 2 and oblique cells ͑22.5 Å by 5.4 Å͒ arranged alternatingly in stacks yielding a molecular layer with lower symmetry and comparatively large crystallographic unit cell. The latter is only observed upon cooling down to 40 K and subsequent annealing to room temperature. For both assemblies typical domain sizes in the range of 100 nm have been found. The EPR results confirm that the radical character is preserved upon adsorption and that the intermolecular distance is smaller than 11 Å. The interaction between the overlapping singly occupied spin orbitals is high, indicating no participation of the unpaired electron in the binding to the surface or laterally between neighboring radicals. The average surface concentration deduced from CV measurements is in excellent agreement with the surface coverages deduced from STM topographies. In aqueous electrolyte the adsorbate undergoes a one-electron oxidation with concomitant loss of a proton as determined from oxidation potential vs pH curves in a similar fashion as known for the free radical in solution. This indicates no dramatic change of the electronic properties of the radical upon adsorption. Structure models are proposed with molecules standing upright like "bicycles in rows."

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Dimerization of organic free radicals in solution.

Cited by 26 publications

References 26 publications

ESR Spectroscopy of Nitroxides: Kinetics and Dynamics of Exchange Reactins

ESR Spectroscopy of Nitroxides: Kinetics and Dynamics of Exchange Reactins

Photophysics of the galvinoxyl free radical revisited

Galvinoxyl monolayers on Au(111) studied by STM, EPR, and cyclic voltammetry

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