Effect of an external magnetic field on the yield of radicals during the photoreduction of xanthene dyes in viscous media

Klimchuk, E. S.; Khudyakov, I. V.; Margulis, Leonid A.; Кузьмин, В. А.

doi:10.1007/bf00952619

Cited by 1 publication

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References 7 publications

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“…For instance, ESR studies of the fluorescein radical anion dissolved in heavy-atom-containing media like Cs + showed ESR resonance line-broadening in viscous solution [45]. In addition, investigations on magnetic-field effects (MFE) [46, 47] involving quantification of the changes in radical concentration in the absence and presence of magnetic fields showed a reduction in the MFE experienced by p-cresol and fluorescein in the presence of external heavy atoms in fairly viscous solution of >3.5 cp/K, corresponding to, for instance, >1,032 cp at 295 K. Negligible effects were observed media below 1cp/K. The above studies suggest that addition of external heavy atoms tends to affect g tensors and hyperfine couplings.…”

Section: Resultsmentioning

confidence: 99%

Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

Cavagnero

2018

Journal of Magnetic Resonance

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Given its short hyperpolarization time (∼10 s) and mostly non-perturbative nature, photo-chemically induced dynamic nuclear polarization (photo-CIDNP) is a powerful tool for sensitivity enhancement in nuclear magnetic resonance. In this study, we explore the extent of H-detectedC nuclear hyperpolarization that can be gained via photo-CIDNP in the presence of small-molecule additives containing a heavy atom. The underlying rationale for this methodology is the well-known external-heavy-atom (EHA) effect, which leads to significant enhancements in the intersystem-crossing rate of selected photosensitizer dyes from photoexcited singlet to triplet. We exploited the EHA effect upon addition of moderate amounts of halogen-atom-containing cosolutes. The resulting increase in the transient triplet-state population of the photo-CIDNP sensitizer fluorescein resulted in a significant increase in the nuclear hyperpolarization achievable via photo-CIDNP in liquids. We also explored the internal-heavy-atom (IHA) effect, which is mediated by halogen atoms covalently incorporated into the photosensitizer dye. Widely different outcomes were achieved in the case of EHA and IHA, with EHA being largely preferable in terms of net hyperpolarization.

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Section: Resultsmentioning

confidence: 99%

Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

Cavagnero

2018

Journal of Magnetic Resonance

View full text Add to dashboard Cite

show abstract

Effect of an external magnetic field on the yield of radicals during the photoreduction of xanthene dyes in viscous media

Cited by 1 publication

References 7 publications

Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

Effect of heavy atoms on photochemically induced dynamic nuclear polarization in liquids

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