Chlorin-type photosensitizers photochemically derived from vinyl porphyrins.
The reaction of singlet oxygen with four vinyl-substituted dicarboxylic porphyrins, vinyldeuteroporphyrin (VD), ethylvinyldeuteroporphyrin (EVD), hydroxyethylvinyldeuteroporphyrin (HVD) and protoporphyrin (PP) in organic solutions is investigated. The main products, the "hydroxyaldehyde" chlorin-type derivatives, are formed with a concentration-dependent photochemical quantum yield that reaches a maximum of 7.4 +/- 1.6 x 10(-3). However, owing to the high turnover of singlet-oxygen production, these chlorin-type compounds are easily prepared photochemically with a chemical yield of 70% and little side product formation. In chemical ionization mass spectrometry, these compounds display an unusual fragmentation with a loss of 16 mass units. This is attributed to the loss of the oxygen bound to the saturated carbon of the modified pyrrole unit. All these compounds sensitize the formation of singlet oxygen with a yield around 0.8. They interact with singlet oxygen with rate constants of 5 x 10(6)-9 x 10(6) M-1 s-1, lower than those measured for vinyl porphyrins. These data are likely to help in the characterization of photoproducts of vinyl porphyrins relevant to photodynamic therapy (PP, HVD). As exemplified with VD and EVD, they also point out the reaction of singlet oxygen as an efficient route to chlorin-type photosensitizers.
Brault
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Laboratoires de Photobiologie et de Biophysique, Muséum National d'Histoire Naturelle, 43 rue Cuvier, 75231 Paris Cedex 05, France. brault@mnhn.fr
Aveline
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B
Delgado
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O
Martin
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MT
D002851:Chromatography, High Pressure Liquid; D003905:Deuteroporphyrins / Q000737:chemistry / Q000528:radiation effects; D007536:Isomerism; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010100:Oxygen / Q000032:analysis / Q000737:chemistry; D010777:Photochemistry; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000528:radiation effects; D011166:Porphyrins / Q000737:chemistry* / Q000528:radiation effects; D011524:Protoporphyrins / Q000737:chemistry / Q000528:radiation effects; D026082:Singlet Oxygen; D013053:Spectrophotometry; D013329:Structure-Activity Relationship; D014753:Vinyl Compounds / Q000737:chemistry* / Q000528:radiation effects
D003905:Deuteroporphyrins; D017319:Photosensitizing Agents; D011166:Porphyrins; D011524:Protoporphyrins; D014753:Vinyl Compounds; D026082:Singlet Oxygen; C006969:chlorin; D010100:Oxygen