Abstract:Peróxidos cíclicos de quatro membros são intermediários de alta energia importantes em diversas transformações quimi e bioluminescentes. Especificamente, a-peroxilactonas (1,2-dioxetanonas) têm sido consideradas sistemas modelo para a eficiente bioluminescência do vaga-lume. Contudo, a preparação deste tipo de compostos altamente instáveis é extremamente difícil e, por isso, apenas alguns poucos grupos de pesquisa puderam estudar as propriedades dessas substâncias. Neste trabalho, a síntese, purificação e cara… Show more
“…The relatively stable a-peroxylactone derivative, spiroadamantyl-1,2-dioxetanone (4), was synthesized according to the published procedure, puried by low-temperature recrystallization and characterized by NMR spectroscopy as reported before. 22 The kinetic assays on the decomposition of the 1,2dioxetanone derivative 4 were performed in toluene as solvent. Initially, the singlet (F S ) and triplet quantum yields (F T ) in its unimolecular decomposition were determined, using two energy acceptors which are known to possess relatively high oxidation potentials and therefore should not lead to signicant catalysed decomposition of the peroxide.…”
Our study on the unimolecular decomposition of a relatively stable 1,2-dioxetanone derivative, model compound for bioluminescence processes, indicates the existence of different reaction pathways for ground and excited state formation.
“…The relatively stable a-peroxylactone derivative, spiroadamantyl-1,2-dioxetanone (4), was synthesized according to the published procedure, puried by low-temperature recrystallization and characterized by NMR spectroscopy as reported before. 22 The kinetic assays on the decomposition of the 1,2dioxetanone derivative 4 were performed in toluene as solvent. Initially, the singlet (F S ) and triplet quantum yields (F T ) in its unimolecular decomposition were determined, using two energy acceptors which are known to possess relatively high oxidation potentials and therefore should not lead to signicant catalysed decomposition of the peroxide.…”
Our study on the unimolecular decomposition of a relatively stable 1,2-dioxetanone derivative, model compound for bioluminescence processes, indicates the existence of different reaction pathways for ground and excited state formation.
“…[44][45][46][47][48] The most difficult preparation is that of the 1,2-dioxetanone derivative 2, which had only been synthesized earlier by Adam's group; we have recently lined out detailed procedures for the synthesis of unstable cyclic peroxides including this derivative 2. 46,48,49 It should be mentioned here that only a few research groups have been able to study the chemiluminescence properties of 1,2-dioxetanone derivatives due to their difficult preparation and extremely low stability. 46,48,49 It should be mentioned here that only a few research groups have been able to study the chemiluminescence properties of 1,2-dioxetanone derivatives due to their difficult preparation and extremely low stability.…”
Section: Resultsmentioning
confidence: 99%
“…46,48,49 The peroxide stock solutions were stored at low temperature (−80°C) and kept at −78°C during the experiments. Diphenyl ether was stirred in the presence of MgSO 4 for 6 hours, after filtration it was distilled under reduced pressure and stored over 4 Å molecular sieves.…”
The effects of the medium viscosity on the chemiexcitation quantum yields of the induced decomposition of 1,2-dioxetanes (highly efficient intramolecular CIEEL system) and the catalyzed decomposition of diphenoyl peroxide and a 1,2-dioxetanone derivative (model systems for the intermolecular CIEEL mechanism, despite their low efficiency) are compared in this work. Quantum yields of the rubrene catalyzed decomposition of diphenoyl peroxide and spiro-adamantyl-1,2-dioxetanone as well as the fluoride induced decomposition of a phenoxy-substituted 1,2-dioxetane derivative are shown to depend on the composition of the binary solvent mixture toluene/diphenyl ether, which possess similar polarity parameters but different viscosities. Correlations of the quantum yield data with the medium viscosity using the diffusional and the frictional (free-volume) models indicate that the induced 1,2-dioxetane decomposition indeed occurs by an entirely intramolecular process and the low efficiency of the intermolecular chemiluminescence systems (catalyzed decomposition of diphenoyl peroxide and 1,2-dioxetanone derivative) is not primarily due to the cage escape of radical ion species.
“…Glassware should be clean and free from metals, especially iron. Treatment of the glassware with a saturated EDTA solution is recommended, followed by carefully washing with deionized water.Depending on the 1,2‐dioxetanone, monitoring of reaction progress by TLC is not possible because of its decomposition on silica gel even at low temperature …”
Four-membered cyclic peroxides are high-energy compounds often associated to cold light emission, but whose chemical and biological roles are still matters of debate. The often-dangerous synthesis of 1,2-dioxetanes, achieved around 50 years ago, has been mastered over the years to a point where some derivatives are commercially available. This fact does not imply that 1,2-dioxetanes can be conveniently prepared in the gram scale or that the synthesis of analogous 1,2-dioxetanones and the elusive 1,2-dioxetanedione are simple. Important questions on the mechanism of chemiluminescence and bioluminescence reactions are under experimental and theoretical scrutiny. The available data have contributed to relate structural and medium effects to the quantum efficiency of these compounds to produce excited states. Consequently, such peroxides have been suggested to produce biologically relevant electronically excited species in vivo in the absence of light. The connection of this hypothesis with melanin-mediated photodamage in the dark has renewed the interest in such cyclic peroxides. This review gives some insight on the synthesis, chemiluminescence mechanism, and biological relevance of 1,2-dioxetanes, 1,2-dioxetanones, and 1,2-dioxetanedione and provides practical protocols for those interested in engaging this field.
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