Photochemical and photosensitizing properties of monomeric and dimeric Sn(IV)-protoporphyrin.
Sn(IV)-protoporphyrin IX (Sn-Pp) in aqueous media exists as a mixture of monomeric and dimeric species, which can be readily distinguished on the basis of their absorption maxima at around 410 and 386 nm respectively. Sn-Pp dimers prevail as the pH is decreased and are characterized by a lower fluorescence quantum yield, a larger tendency to undergo photobleaching and a reduced photosensitizing efficiency compared with the Sn-Pp monomer. The photosensitizing action of Sn-Pp appears to involve the intermediacy of singlet oxygen (1O2) as shown by photo-oxidation studies with N-acetyl-tryptophanamide in light and deuterated water solutions. Using 1,3-diphenyl-isobenzofuran as a substrate, the quantum yield of 1O2 generation by monomeric Sn-Pp was found to be about 0.6.
Reddi
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E
Department of Biology, University of Padova, Italy.
Jori
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G
Rubaltelli
F F
FF
D008665:Metalloporphyrins / Q000737:chemistry*; D011524:Protoporphyrins / Q000737:chemistry*; D011838:Radiation-Sensitizing Agents / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D013329:Structure-Activity Relationship
D008665:Metalloporphyrins; D011524:Protoporphyrins; D011838:Radiation-Sensitizing Agents; C032628:tin protoporphyrin IX