Type I and Type II Photosensitized Oxidation Reactions : Guidelines and Mechanistic Pathways.
Here, 10 guidelines are presented for a standardized definition of type I and type II photosensitized oxidation reactions. Because of varied notions of reactions mediated by photosensitizers, a checklist of recommendations is provided for their definitions. Type I and type II photoreactions are oxyg...
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| Autores principales: | , , , , , , , , , , , |
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| Formato: | Articulo Preprint |
| Lenguaje: | Español |
| Publicado: |
2017
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| Materias: | |
| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/107822 http://europepmc.org/backend/ptpmcrender.fcgi?accid=PMC5500392&blobtype=pdf |
| Aporte de: |
| Sumario: | Here, 10 guidelines are presented for a standardized definition of type I and type II photosensitized oxidation reactions. Because of varied notions of reactions mediated by photosensitizers, a checklist of recommendations is provided for their definitions. Type I and type II photoreactions are oxygendependent and involve unstable species such as the initial formation of radical cation or neutral radicals from the substrates and/or singlet oxygen (<sup>1</sup>O<sub>2</sub> <sup>1</sup>Δ<sub>g</sub>) by energy transfer to molecular oxygen. In addition, superoxide anion radical (O2←) can be generated by a charge-transfer reaction involving O2 or more likely indirectly as the result of O2-mediated oxidation of the radical anion of type I photosensitizers. In subsequent reactions, O2← may add and/or reduce a few highly oxidizing radicals that arise from the deprotonation of the radical cations of key biological targets. O2← can also undergo dismutation into H<sub>2</sub>O<sub>2</sub>, the precursor of the highly reactive hydroxyl radical (OH) that may induce delayed oxidation reactions in cells. In the second part, several examples of type I and type II photosensitized oxidation reactions are provided to illustrate the complexity and the diversity of the degradation pathways of mostly relevant biomolecules upon one-electron oxidation and singlet oxygen reactions. |
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