Synthesis and characterization of a biocompatible 13C1 isotopologue of trityl radical OX071 for in vivo EPR viscometry

Poncelet, Martin; Ngendahimana, Thacien; Gluth, Teresa D; Hoblitzell, E Hannah; Eubank, Timothy D.; Eaton, Gareth R.; Driesschaert, Benoît

doi:10.1039/d2an01527g

Cited by 4 publications

(4 citation statements)

References 26 publications

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“…Another class of highly persistent triarylmethyls is illustrated by the structure of Finland trityl ( FT ) radical and its more hydrophilic version Ox-063 . − Analogous to PTM or TTM , here the persistence is attained by severe out-of-plane twisting of the ortho-substituted aryl rings. Both radicals are monomeric and persistent at ambient conditions, and especially Ox-063 and Ox-063-d 24 are well soluble in water, biocompatible and lacking of interactions with blood albumin . Because of negligible hyperfine couplings and the g -values that are close to that of the free electron, derivatives of both FT and Ox radicals feature relatively narrow electron paramagnetic resonance (EPR) lines and possess relatively long electron spin relaxation times ( T m and T 1 ) .…”

Section: Persistent and Stable Monoradicals As Spin Centersmentioning

confidence: 99%

“…Because of negligible hyperfine couplings and the g -values that are close to that of the free electron, derivatives of both FT and Ox radicals feature relatively narrow electron paramagnetic resonance (EPR) lines and possess relatively long electron spin relaxation times ( T m and T 1 ) . Their derivatives found applications as dynamic nuclear polarization (DNP) agents in NMR, − as oxygen and pH sensors in biomedicine, and as spin labels in biophysics, e.g., derivatives of FT or Ox-063-d 24 for EPR distance measurements, − especially at up to 150 K in cell , and at room temperature in vitro. − 13 C-labeled (at center C) Ox-063-d 24 and its derivatives possess enhanced anisotropy of the hyperfine coupling, providing a relatively wide EPR spectrum that is also sensitive to molecular tumbling; this allows for applications such as viscosity sensors in biomedicine and spin labels for distance measurements using widely available double electron–electron resonance (DEER) spectroscopy …”

Section: Persistent and Stable Monoradicals As Spin Centersmentioning

confidence: 99%

“…50 Their derivatives found applications as dynamic nuclear polarization (DNP) agents in NMR, 51−54 as oxygen and pH sensors in biomedicine, 55 and as spin labels in biophysics, e.g., derivatives of FT or Ox-063-d 24 for EPR distance measurements, 56−62 especially at up to 150 K in cell 60,61 and at room temperature in vitro. 56−58 13 C-labeled (at center C) Ox-063-d 24 and its derivatives possess enhanced anisotropy of the hyperfine coupling, providing a relatively wide EPR spectrum that is also sensitive to molecular tumbling; 63 this allows for applications such as viscosity sensors in biomedicine 49 and spin labels for distance measurements using widely available double electron−electron resonance (DEER) spectroscopy. 62 The Koelsch radical, 1,3-bisdiphenylene-2-phenylallyl (BDPA), is also historically unique as it was the first carbonbased radical to display no significant reactivity toward oxygen; at the time, this was so unprecedented that the original Koelsch's manuscript was rejected in the 1930s and forgotten for nearly 30 years.…”

Section: Carbon-centered Monoradicalsmentioning

confidence: 99%

“…Both radicals are monomeric and persistent at ambient conditions, and especially Ox-063 and Ox-063-d 24 are well soluble in water, biocompatible and lacking of interactions with blood albumin. 49 Because of negligible hyperfine couplings and the g-values that are close to that of the free electron, derivatives of both FT and Ox radicals feature relatively narrow electron paramagnetic resonance (EPR) lines and possess relatively long electron spin relaxation times (T m and T 1 ). 50 Their derivatives found applications as dynamic nuclear polarization (DNP) agents in NMR, 51−54 as oxygen and pH sensors in biomedicine, 55 and as spin labels in biophysics, e.g., derivatives of FT or Ox-063-d 24 for EPR distance measurements, 56−62 especially at up to 150 K in cell 60,61 and at room temperature in vitro.…”

Section: Carbon-centered Monoradicalsmentioning

confidence: 99%

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From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals

Shu,

Yang,

Rajca

2023

Chem. Rev.

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Stable radicals and thermally robust high-spin di-and triradicals have emerged as important organic materials due to their promising applications in diverse fields. New fundamental properties, such as SOMO/HOMO inversion of orbital energies, are explored for the design of new stable radicals, including highly luminescent ones with good photostability. A relation with the singlet−triplet energy gap in the corresponding diradicals is proposed. Thermally robust high-spin di-and triradicals, with energy gaps that are comparable to or greater than a thermal energy at room temperature, are more challenging to synthesize but more rewarding. We summarize a number of high-spin di-and triradicals, based on nitronyl nitroxides that provide a relation between the experimental pairwise exchange coupling constant J/k in the high-spin species vs experimental hyperfine coupling constants in the corresponding monoradicals. This relation allows us to identify outliers, which may correspond to radicals where J/k is not measured with sufficient accuracy. Double helical high-spin diradicals, in which spin density is delocalized over the chiral π-system, have been barely explored, with the sole example of such high-spin diradical possessing alternant π-system with Kekuléresonance form. Finally, we discuss a high-spin diradical with electrical conductivity and derivatives of triangulene diradicals.

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