ESR and theoretical studies of trimer radical cations of coronene

Komaguchi, Kenji; Nomura, K.; Shiotani, Masaru; Lund, Anders; Jansson, Magnus; Lunell, Sten

doi:10.1016/j.saa.2005.04.039

Cited by 14 publications

(15 citation statements)

References 22 publications

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“…1.6 mT, which is calculated according to the reported hyperfine structures of the coronene cation radical and that of the odV •+ radical, as speculated from data reported for the ethyl viologen monocation radical. 58,59 The experimental values are comparable with the theoretical values, which indicates that the dominant mechanism for spin state mixing is coherent hyperfine mixing. Although the slightly larger experimental values may be due to a small contribution of relaxation/ dephasing mechanisms, the radical pair lifetimes for both singlet-and triplet-born components are considered to be much shorter than the spin relaxation times (ca.…”

Section: ■ Results and Discussionsupporting

confidence: 70%

Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studied by Magnetic Field Effect

Miura

2013

J. Phys. Chem. B

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Spin selectivity in long-lived charge separation at the micellar interface is studied using the magnetic field effect (MFE). An amphiphilic viologen is complexed with a nonionic surfactant to form a supramolecular acceptor cage, of which the size is controlled by the acceptor concentration, as confirmed by dynamic light scattering measurement. Photoinduced electron transfer (ET) from a guest polyaromatic molecule to the viologen moiety is observed spin-dependently with time-resolved fluorescence (trFL) and transient absorption (TA). A negative MFE on the radical yield is successfully observed, which indicates generation of singlet-born long-lived radical pair that is realized by supramolecular control of the donor-acceptor (D-A) distances. The dominance of the singlet-precursor MFE is sensitive to the acceptor concentration, which presumably affects the D-A distance as well as the cage size. However, theoretical analysis of the MFE gives large recombination rates of ca. 10(8) s(-1), which indicate the contribution of spin-allowed recombination of the pseudocontact radical pair generated by still active in-cage diffusion. Dependence of the viologen concentration and alkyl chain length on the recombination and escape dynamics is discussed in terms of precursor spin states and the microenvironments in the cage.

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Section: ■ Results and Discussionsupporting

confidence: 70%

Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studied by Magnetic Field Effect

Miura

2013

J. Phys. Chem. B

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“…The linewidths of the Lorentzian fits are 0.086 and 0.055 mT, respectively. The average g factor (2.0029) is comparable to the g factor (2.0026) for coronene cations oxidized by H 2 SO 4 ,24 SO 2 /BF 3 ,24 and (CF 3 CO 2 ) 3 Tl,25 which also confirms the presence of cationic coronene species in solid 1 .…”

Section: Resultssupporting

confidence: 58%

Isotropic Three‐Dimensional Molecular Conductor Based on the Coronene Radical Cation

et al. 2014

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In this study, we obtained the first cation radical solid of a highly symmetric (D6h) polyaromatic hydrocarbon, coronene, by electrooxidation. The (coronene)3Mo6Cl14 salt, which is formed with an Oh‐symmetric molybdenum cluster unit Mo6Cl142–, has an isotropic cubic structure with Pm$\bar {3}$m symmetry. The presence of two orientations for the coronene molecules related by an in‐plane 90° rotation (merohedral disorder) allows for fourfold symmetry along the <100> direction. The disorder has dynamic features because 2H NMR spectroscopic studies revealed that the coronene molecules undergo an in‐plane flipping motion. The observation of two motional sites with significantly different rotational rates (300 Hz and 5 MHz at 103 K) in an approximate 2:1 ratio appears to be consistent with the splitting of a Raman‐active A1g mode, confirming a random charge‐disproportionated state instead of a uniform partially‐charged state. The slower‐ and faster‐rotating species are assigned to charge‐rich and charge‐poor coronenes, respectively, with respect to C–H···Cl hydrogen bonds with neighboring Mo6Cl142– cluster units. The electrical conductivity of the salt is rather high but is well‐described by a three‐dimensional (3D) variable‐range hopping mechanism, which is possibly associated with the random charge disproportionation. These results provide a significant step forward in developing an isotropic 3D π‐conducting system composed of planar π‐conjugated molecules.

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“…The isotropic ESR spectra of the trimer radical cation of coronene were simulated exactly using the EasySpin software available at https://www.easyspin.org/. The proton hyperfine coupling constants in Table 3 were used to simulate the spectra predicted by the DFT calculations in this work, by an experimental analysis, 21 and by an interpretation 22 of the spectrum obtained by Willigen et al 20…”

Section: Esr Simulation Methodsmentioning

confidence: 99%

“…Based on an analysis of the previously published data, 20 a staggered sandwich structure was proposed for the ''global'' minimum of the trimer cation with hfcc's of 0.122 (12H) and 0.015 (24H), respectively. 22 Thus, the experimental data have been accumulated gradually. However, a structure that satisfies the previous experimental findings has not been determined yet.…”

Section: Introductionmentioning

confidence: 99%

Structures and electronic states of trimer radical cations of coronene: DFT–ESR simulation study

Tachikawa

Lund

2022

Phys. Chem. Chem. Phys.

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ESR and theoretical studies of trimer radical cations of coronene

Cited by 14 publications

References 22 publications

Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studied by Magnetic Field Effect

Supramolecular Control of the Spin-Dependent Dynamics of Long-Lived Charge-Separated States at the Micellar Interface As Studied by Magnetic Field Effect

Isotropic Three‐Dimensional Molecular Conductor Based on the Coronene Radical Cation

Structures and electronic states of trimer radical cations of coronene: DFT–ESR simulation study

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