Electron Spin Resonance of Radical Cations Produced by the Oxidation of Aromatic Hydrocarbons with SbCl5

Lewis, I.C.; Singer, L. S.

doi:10.1063/1.1697200

Cited by 285 publications

(103 citation statements)

References 37 publications

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“…We have determined the energetic position of the polaron absorption bands in the infrared by chemical doping with the oxidizing dopant SbCl 5 and quantum-chemical calculations 32,33 . SbCl 5 is known to be a strong oxidizing agent and to generate a hole-polaron in the ground state of most conjugated polymers 34,35 . Figure 2i-l shows the corresponding dopant induced variation in the optical density spectra (solid curves), measured by adding a small amount of SbCl 5 (4% weight) to the respective polymers.…”

Section: Lowmentioning

confidence: 99%

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

et al. 2012

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Polymeric semiconductors are materials where unique optical and electronic properties often originate from a tailored chemical structure. This allows for synthesizing conjugated macromolecules with ad hoc functionalities for organic electronics. In photovoltaics, donoracceptor co-polymers, with moieties of different electron affinity alternating on the chain, have attracted considerable interest. The low bandgap offers optimal light-harvesting characteristics and has inspired work towards record power conversion efficiencies. Here we show for the first time how the chemical structure of donor and acceptor moieties controls the photogeneration of polaron pairs. We show that co-polymers with strong acceptors show large yields of polaron pair formation up to 24% of the initial photoexcitations as compared with a homopolymer (η = 8%). π-conjugated spacers, separating the donor and acceptor centre of masses, have the beneficial role of increasing the recombination time. The results provide useful input into the understanding of polaron pair photogeneration in low-bandgap co-polymers for photovoltaics.

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Section: Lowmentioning

confidence: 99%

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

et al. 2012

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“…Schon frühzeitig wurde nach dem ESR-spektroskopischen Nachweis eines (CioH8)2 + ' [9] für die hier interessierenden Radikalkationen von reinen Kohlenwasserstoffen in Lösung [5 a] und für Excimere [33] eine parallele Anordnung der Ringsysteme postuliert. Zumindest für den Fall des Pyrens wurden ferner ähnliche Gleichgewichts-Konfigurationen des Excimeren in Lösung und eines Paares benachbarter Moleküle im Kristall hergeleitet.…”

Section: Schlußfolgerungenunclassified

“…Längere Lebensdauern wurden für Radikalkationen kleiner, polyfluorierter Aromaten [6,7] oder von Anthracen [8] in Lösung beschrieben, wie man überhaupt von vielen mehrkernigen Aromaten Radikalkationen enthaltende Lösungen erhalten kann (z.B. allerdings bei tiefen Temperaturen im System H2CCl2/SbCls [9]). Den am längsten bekannten Fall eines isolierten Radikalkation-geeignete sterische Konfiguration Wechselwirkungen zu den Kohlenwasserstoff-jr-Systemen ausbilden, die, wie für die CF3-Gruppe bekannt [17], zur Stabilisierung beitragen.…”

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Elektrochemische Synthesen, XIV [1] Radikalkation-Salze des Naphthalins / Electrochemical Syntheses, XIV [1]. Radical Cation Salts of Naphthalene

Fritz¹,

Gebauer²,

Friedrich³

et al. 1978

Zeitschrift Für Naturforschung B

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Abstract By anodic oxidation of naphthalene in H2CCl2/O.O2m Bu4NPF6 at -45 °C dark red-violet crystals of (C10H8)2PF6 can be obtained by electrocrystallisation. They are stable at low temperatures, however, decompose on warming. In solution and in the polycrystalline state these radical cation salts show only narrow e.p.r. signals without h.f.s. The specific conductivity of a polycrystalline pellet at room temperature was determined to be 0.12 ±0.046 Ohm-1 cm-1 . The structure determination of (C10H8)2PF6 yielded the tetragonal space group P42/n, Z = 2, a = b = 1156(2), c = 640(1) pm. Patterson synthesis and difference Fourier analyses showed the compound to have a columnar stacking of C10H8 units the long molecular axes of which are twisted alternately by 90° around a screw axis in c-direction, and the molecular planes of which are 320 pm apart. The PF6-ions have four nearest C10H8 neighbours lying in pairs in parallel planes 63 pm above and below that plane of PF6- perpendicular to the c-axis and containing a PF4 group. This is the first established case for a columnar structure of a pure hydrocarbon radical cation. (C10H8)2AsF6 is isomorphous.

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“…A u t h o r ' s P o s t -p r i n t Table 1 Effective hyperfine coupling constants in mT for radical pairs formed by the electron donors and acceptors used in this study, calculated from literature values [16][17][18][19] using Eq. 13.…”

Section: Simulation Methodsmentioning

confidence: 99%

Spin-locking in low-frequency reaction yield detected magnetic resonance

Wedge

Lau

Ferguson

et al. 2013

Phys. Chem. Chem. Phys.

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The purported effects of weak magnetic fields on various biological systems from animal magnetoreception to human health have generated widespread interest and sparked much controversy in the past decade. To date the only well established mechanism by which the rates and yields of chemical reactions are known to be influenced by magnetic fields is the radical pair mechanism, based on the spin-dependent reactivity of radical pairs. A diagnostic test for the operation of the radical pair mechanism was proposed by Henbest et al. [J. Am. Chem. Soc., 2004, 126, 8102] based on the combined effects of weak static magnetic fields and radiofrequency oscillating fields in a reaction yield detected magnetic resonance experiment. Here we investigate the effects on radical pair reactions of applying relatively strong oscillating fields, both parallel and perpendicular to the static field. We demonstrate the importance of understanding the effect of the strength of the radiofrequency oscillating field; our experiments demonstrate that there is an optimal oscillating field strength above which the observed signal decreases in intensity and eventually inverts. We establish the correlation between the onset of this effect and the hyperfine structure of the radicals involved, and identify the existence of 'overtone' type features appearing at multiples of the expected resonance field position.

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Electron Spin Resonance of Radical Cations Produced by the Oxidation of Aromatic Hydrocarbons with SbCl5

Cited by 285 publications

References 37 publications

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

Structural correlations in the generation of polaron pairs in low-bandgap polymers for photovoltaics

Elektrochemische Synthesen, XIV [1] Radikalkation-Salze des Naphthalins / Electrochemical Syntheses, XIV [1]. Radical Cation Salts of Naphthalene

Spin-locking in low-frequency reaction yield detected magnetic resonance

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