Characterization of the excited-state reactivity of a persistent aryl-substituted allyl free radical

Breslin, David T.; Fox, Marye Anne

doi:10.1021/j100152a045

Cited by 22 publications

(37 citation statements)

References 8 publications

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“…BDPA in dichloromethane has similar absorption maxima, which are 485 and 859 nm, respectively. 12,14 Similar to BDPA, SA-BDPA is reduced under basic conditions (e.g., aqueous NaOH in the presence of catalytic amounts of acetone, THF, DMSO, or ascorbate). The resulting SA-BDPA − anion ( 2 ) can be re-oxidized to 3 chemically (e.g., by AgNO 3 ) or electrochemically.…”

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confidence: 99%

Water-Soluble Narrow-Line Radicals for Dynamic Nuclear Polarization

et al. 2012

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The synthesis of air-stable highly water-soluble organic radicals containing a 1,3-bisdiphenylene-2-phenylallyl (BDPA) core is reported. A sulfonated derivative, SA-BDPA, retains the narrow EPR linewidth (<30 MHz at 5 T) of the parent BDPA in highly concentrated glycerol/water solutions (40 mM), which enables its use as polarizing agent for solid effect dynamic nuclear polarization (SE DNP). Sensitivity enhancement of 110 was obtained in high field magic-angle-spinning nuclear magnetic resonance (MAS NMR) experiments. The ease of synthesis and high maximum enhancements obtained with the BDPA-based radicals constitute a major advance over the trityl-type narrow line polarization agents.

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confidence: 99%

Water-Soluble Narrow-Line Radicals for Dynamic Nuclear Polarization

et al. 2012

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“…NaOH). Both AgNO 3 and K 3 Fe(CN) 6 , the oxidizing agents commonly used for the oxidation of the carbanion to the radical, yielded similar results (Figure and Figure S4). Reaction in DMSO: t BuOH (9:1) with t BuOK followed by oxidation with AgNO 3 , the conditions reported for the generation of biradical 3 , led to ca.…”

Section: Resultsmentioning

confidence: 99%

On the Limited Stability of BDPA Radicals

Mandal

Sigurdsson

2020

Chemistry A European J

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1,3‐Bis(diphenylene)‐2‐phenylallyl (BDPA)‐based radicals are of interest as polarizing agents for dynamic nuclear polarization (DNP). For this purpose, a BDPA‐nitroxide biradical, employing a phosphodiester linkage, was synthesized. Contrary to what is commonly assumed, BDPA‐derived radicals were observed to have limited stability. Hence, the effects of various factors on the stability of BDPA radicals were investigated. Solvent polarity was found to play a significant role on degradation; a polar BDPA radical was observed to degrade faster in a non‐polar solvent, whereas non‐polar radicals were more unstable in polar solvents. The rate of decomposition was found to increase non‐linearly with increasing radical concentration; a 2‐fold increase in concentration led to a 3‐fold increase in the rate of degradation. Collectively, these results indicate that the dimerization is a significant degradation pathway for BDPA radicals and indeed, a dimer of one BDPA radical was detected by mass spectrometry.

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“…The reference radical 8 is remarkably stable to oxygen in the solid state 32 and has been reported to be stable to oxygen in solution with the exclusion of light. 33 However, to achieve the highest persistance in solution in the dark it is necessary the presence of benzene which forms a complex with the radical. 33 On the other hand, BDPA radical is reduced to give the corresponding carbanion when exposed to strong bases, such as hydroxide or alkoxide, and also reacts with strong acids.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…33 However, to achieve the highest persistance in solution in the dark it is necessary the presence of benzene which forms a complex with the radical. 33 On the other hand, BDPA radical is reduced to give the corresponding carbanion when exposed to strong bases, such as hydroxide or alkoxide, and also reacts with strong acids. 32 Radical 8 was firstly synthesized by the Koelsch's method.…”

Section: Synthesis and Characterizationmentioning

confidence: 99%