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Abstract Dioxetane intermediates readily decompose to chemiluminescent triplet carbonyls, giving rise to what has been paradoxically called photochemistry in the dark. In this issue ofPhotochemistry and Photobiology, Bechara et al. report on mechanistic advances in such a reaction. With the use of horseradish peroxidase for isobutyraldehyde‐derived triplet acetone, light emission from acetone and singlet oxygen can be quenched. The experiments reveal that the reaction depends on oxygen and the amino acid. The analysis reveals that free tryptophan is a target of this form of “carbonyl stress,” with the efficient formation of mono‐, bi‐ and tricyclic compounds (N‐formylkynurenine, indoline, 1λ2‐indole and 3H‐indoles).
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Oxygen‐Sensing Chemiluminescent Iridium(III) 1,2‐Dioxetanes: Unusual Coordination and Activity
Abstract Next generation chemiluminescent iridium 1,2‐dioxetane complexes have been developed which consist of the Schaap's 1,2‐dioxetane scaffold directly attached to the metal center. This was achieved by synthetically modifying the scaffold precursor with a phenylpyridine moiety, which can act as a ligand. Reaction of this scaffold ligand with the iridium dimer [Ir(BTP)2(μ‐Cl)]2(BTP=2‐(benzo[b]thiophen‐2‐yl)pyridine) yielded isomers which depict ligation through either the cyclometalating carbon or, interestingly, the sulfur atom of one BTP ligand. Their corresponding 1,2‐dioxetanes display chemiluminescent responses in buffered solutions, exhibiting a single, red‐shifted peak at 600 nm. This triplet emission was effectively quenched by oxygen, yielding in vitro Stern‐Volmer constants of 0.1 and 0.009 mbar−1for the carbon‐bound and sulfur compound, respectively. Lastly, the sulfur‐bound dioxetane was further utilized for oxygen sensing in muscle tissue of living mice and xenograft models of tumor hypoxia, depicting the ability of the probe chemiluminescence to penetrate biological tissue (total flux ∼106 p/s).
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- Award ID(s):
- 2155170
- PAR ID:
- 10381341
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Analysis & Sensing
- Volume:
- 3
- Issue:
- 1
- ISSN:
- 2629-2742
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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