Radical pair dynamics in anionic micelles with different alkyl chain length as studied by pulse-mode product-yield-detected ESR

Konishi, Yukiko; Okazaki, Masaharu

doi:10.1007/bf03162089

Cited by 4 publications

(2 citation statements)

References 26 publications

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“…It is seen that the kinetic model thus represents the concentration dependences of the MFEs very well, both at short and long times. Whereas the quenching rate constant k 2 differs by less than 20 % from the one found in homogeneous solution, [6] k 1 is an order of magnitude lower than the values reported for hydrogen abstraction from SDS by triplet benzophenone, [25][26][27] which were obtained by RYDMR (reaction-yield-detected magnetic resonance) measurements. The most likely reason is a different electronic configuration of the triplet, np* in the case of benzophenone and pp* in the case of xanthone.…”

Section: Resultscontrasting

confidence: 54%

Quenching Mechanisms and Diffusional Pathways in Micellar Systems Unravelled by Time‐Resolved Magnetic‐Field Effects

Goez

Henbest

Windham

et al. 2009

Chemistry A European J

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Magnetic-field effects (MFEs) are used to investigate the photoreaction of xanthone (A) and DABCO (D) in anionic (SDS) or cationic (DTAC) micelles at high pH (DABCO = 1,4-diazabicyclo[2.2.2]octane, SDS = sodium dodecyl sulfate, DTAC = dodecyl trimethyl ammonium chloride). From MFE experiments with nanosecond time resolution, the radical anion A(.)(-) can be observed without any interference from the much more strongly absorbing triplet (3)A*, the different quenching processes can be separated and their rates can be measured. Triplet (3)A* is quenched dynamically both by the SDS micelle (k(1) = 5.0x10(5) s(-1)) and by DABCO approaching from the aqueous phase (k(2) = 2.0x10(9) M(-1) s(-1)). Static quenching by solubilised DABCO (association constant with the SDS micelles, 1.5 M(-1)) also participates at high DABCO concentrations, but is chemically nonproductive and does not lead to MFE generation. The MFEs stemming from the radical ion pairs A(.)(-) D(.)(+) are about 40 times larger in the anionic micelles than in the cationic ones despite a higher yield of free radicals in the latter case. This can be rationalised by different diffusional dynamics: Because of the location of their precursors, A(.)(-) and D(.)(+) are formed at opposite sides of the micelle boundary. Subsequently, the negatively charged Stern layer of the SDS micelle traps the radical cation, which then undergoes surface diffusion, so both the recombination probability and the spin mixing are high; in contrast, the positive surface charge of the DTAC micelle forces the radical cation into the bulk of the solution, thus efficiently blocking a recombination.

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Section: Resultscontrasting

confidence: 54%

Quenching Mechanisms and Diffusional Pathways in Micellar Systems Unravelled by Time‐Resolved Magnetic‐Field Effects

Goez

Henbest

Windham

et al. 2009

Chemistry A European J

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“…This is a nice demonstration of the reaction control by the spin operation under the magnetic resonance conditions. Okazaki and coworkers further extended their work [113][114][115].…”

Section: Controlling Photochemical Reactionsmentioning

confidence: 99%

Developments of magnetic-resonance-related spin chemistry in Japan

et al. 2003

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Abstraet. A review on the developments of the magnetic-resonance-related spin chemistry in Japan is presented. We describe how studies in this atea started in Japan and developed into the flourishing state of the present. Important contributions made by Japanese spin chemists in the last two decades in three areas, namely, work on chemically induced dynamic electron polarization, excited states and controlling of photochemical reactions, are presented. More emphases are placed on the new deveIopments in recent years, particularty new concepts and new methodologies.

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Ionic liquid-based microwave-assisted extraction of verbascoside from Rehmannia root

Fan

et al. 2018

Industrial Crops and Products

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Radical pair dynamics in anionic micelles with different alkyl chain length as studied by pulse-mode product-yield-detected ESR

Cited by 4 publications

References 26 publications

Quenching Mechanisms and Diffusional Pathways in Micellar Systems Unravelled by Time‐Resolved Magnetic‐Field Effects

Quenching Mechanisms and Diffusional Pathways in Micellar Systems Unravelled by Time‐Resolved Magnetic‐Field Effects

Developments of magnetic-resonance-related spin chemistry in Japan

Ionic liquid-based microwave-assisted extraction of verbascoside from Rehmannia root

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