Chemical polarization of nuclei in reactions of photoreduction of benzophenone and the effect of a heavy atom

Yankelevich, A. Z.; Khudyakov, I. V.; Levin, P. P.; Serebrennikov, Yu. A.

doi:10.1007/bf00953691

Cited by 1 publication

(2 citation statements)

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“…A representative case is that of benzophenone dyes acting upon phenols and anilines and substrates. For instance, a covalent bromo derivative of benzophenone reduces photo-CIDNP enhancements [36].…”

Section: Resultsmentioning

confidence: 99%

“…For instance, the site-specific complete suppression of photo-CIDNP observed upon the selective labeling of specific Tyr as 3-I-Tyr in insulin has been exploited as an aid in the resonance assignment process [37]. Finally, the CIDNP enhancement of photo-excited p-bromo dibenzyl ketone, acting both as a substrate and a dye, is much lower than that of benzyl ketone [36].…”

Section: Resultsmentioning

confidence: 99%

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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%

Section: Resultsmentioning

confidence: 99%