Magnetic field effects and CIDEP due to the d-type triplet mechanism in intra-molecular reactions

Hayashi, H.; Sakaguchi, Yoshio

doi:10.1016/j.jphotochemrev.2005.01.001

Cited by 12 publications

(3 citation statements)

References 30 publications

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“…The HFI provides a "torque" that promotes the electron spin flip in one radical, which means that a T-S transition takes place in the RP. This, the most popular RP mechanism of CIDNP, has also been applied to chemically induced dynamic electron polarization (CIDEP) in EPR spectra of radical products in photochemistry as well as to magnetic field effects (MFE) in chemistry (Salikhov et al, 1984;Hayashi & Sakaguchi, 2005). In non-geminate radical pairs, produced from different precursors, all possible spin states are equally probable.…”

Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

“…2). In 1979, Steiner reported MFE due to the depopulation type triplet mechanism (d-type TM) on the radical yield of electron transfer reactions between a triplet-excited cationic dye ( 3 A + *) and Br-substituted anilines (D) in methanol at 300 K (Hayashi & Sakaguchi, 2005). Steiner proposed that a triplet exciplex 3 (A*D + ) is generated by charge transfer in this reaction and that the sublevel-selective depopulation is induced by strong SOC at a heavy Br atom during decomposition 3 (A*D + ) = A • + D •+ .…”

Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

“…Similar reactions with triplet exciplexes were found to produce CIDEP and MFE due to d-type TM. The corresponding theory of magnetic field effects due to spin-orbit coupling in transient intermediates and d-type TM has been proposed (Hayashi & Sakaguchi, 2005;Serebrennikov & Minaev, 1987). Its application for charge-transfer excitons in phosphorescent OLEDs is ongoing.…”

Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

See 2 more Smart Citations

Organometallic Materials for Electroluminescent and Photovoltaic Devices

Минаев¹,

Ågren²,

Tian³

et al. 2011

Organic Light Emitting Diode - Material, Process and Devices

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Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

Section: Spin Dynamics In Organic Solvents and Its Relation To Oled Ementioning

confidence: 99%

See 1 more Smart Citation

Organometallic Materials for Electroluminescent and Photovoltaic Devices

Минаев¹,

Ågren²,

Tian³

et al. 2011

Organic Light Emitting Diode - Material, Process and Devices

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Long Persistent Phosphorescence of Crystalline Phenylboronic Acid Derivatives: Photophysics and a Mechanistic Study

et al. 2017

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Room‐temperature phosphorescence (RTP) of crystalline isophthalic acid (IPA) through hyperfine‐coupling‐driven (HFC‐driven) intersystem crossing in charge‐transfer (CT) complexes has been discovered recently, giving rise to a new design method for phosphorescence materials and photosensitizers. In this study, we found that crystalline phenylboronic acid (PB) derivatives also demonstrated RTP, as recorded for IPA. Magnetic‐field and spin‐isotope effects on the emission strength intensities of PBs were typical of HFC‐driven phosphorescence. p‐Halogenated PB esters exhibited a heavy‐atom effect with a shortened emission lifetime as expected from the study of IPA. Unlike IPA, the esters of PBs also showed RTP, which facilitates a study of the structure/photophysical property relationships by exchanging ester head groups. We then addressed a question: do PB esters with a bulky head group prohibit CT formation and thus phosphorescence? As a result, a bulky PB ester with large intermolecular distances in its crystalline form showed neither CT absorptions nor phosphorescence, confirming the significance of CT formation in the HFC mechanism.

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The Excited Triplet State of Azoalkanes: Electron Spin Polarization and Magnetic Field Effects During Triplet-Sensitized Photolysis of trans-Azocumene in Solution

Milikisiyants

Steiner

Paul³

2011

Appl Magn Reson

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The triplet-sensitized photodecomposition of azocumene into nitrogen and cumyl radicals is investigated by time-resolved electron paramagnetic resonance and absorption spectroscopy. The radicals are found to be created spin polarized with a yield depending on the strength of the applied magnetic field. The phenomenon arises because in triplet azocumene, the decay into radicals competes with a fast triplet-sublevel selective intersystem crossing back to the azocumene ground state. The size of the initial spin polarization of the radicals and the magnetic field effect on their yield are determined in solvents of different viscosities. Data analysis yields rate constants for the intersystem crossing and the cleavage reaction of triplet azocumene as well as its zero-field splitting D ZFS. At room temperature in nonpolar solvents, the most probable values are: k x = k y = 1.2 × 1011 s−1 and k z = 1.9 × 1010 s−1 for the intersystem crossing from the energetically lower and upper triplet substates, respectively, k p = 1.6 × 109 s−1 for the cleavage reaction and for the zero-field splitting D ZFS = −3.4 × 1010 s−1 (0.18 cm−1).

show abstract

Magnetic field effects and CIDEP due to the d-type triplet mechanism in intra-molecular reactions

Cited by 12 publications

References 30 publications

Organometallic Materials for Electroluminescent and Photovoltaic Devices

Organometallic Materials for Electroluminescent and Photovoltaic Devices

Long Persistent Phosphorescence of Crystalline Phenylboronic Acid Derivatives: Photophysics and a Mechanistic Study

The Excited Triplet State of Azoalkanes: Electron Spin Polarization and Magnetic Field Effects During Triplet-Sensitized Photolysis of trans-Azocumene in Solution

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