| Autor: |
Nina Kuznetsova, Dmitry Makarov, Olga Yuzhakova, Anton Strizhakov, Yana Roumbal, Ludmila Ulanova, Alexander Krasnovsky, Oleg Kaliya |
| Předmět: |
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| Zdroj: |
Photochemical & Photobiological Sciences; Dec2009, Vol. 8 Issue 12, p1724-1733, 10p |
| Abstrakt: |
The photophysical and photosensitizing properties of two octacationic oxotitanium phthalocyanines (TiOPcs), bearing pyridiniomethyl or cholinyl substituents, have been studied in aqueous and alcohol solutions. In water, both compounds were monomeric with the high quantum yields of fluorescence (ΦF= 0.17–0.19) and singlet oxygen formation (ΦΔ= 0.4–0.5). The ΦFand ΦΔof both phthalocyanines decreased with the increase of solvent hydrophobicity from water to ethanol. This effect was much stronger in alcohol solutions of the pyridiniomethyl-substituted phthalocyanine and probably results from aggregation of TiOPc molecules caused by association of chloride anions with phthalocyanine cationic groups. Evidence is presented that under illumination aqueous TiOPc solutions also produce hydroxyl radicals, which probably appear owing to photocleavage of water molecules. The quantum yield of OH formation was (3–5) × 10−5after argon purging and twice as much in the presence of air. It is shown that irradiation of TiOPc solutions causes photobleaching of TiOPcs. The photobleaching quantum yield in water was found to be about 1 × 10−4. The data suggest that photobleaching occurs owing to the reactivity of hydroxyl radicals, though singlet oxygen is generated by TiOPcs much more efficiently. The phototoxicity of the tested TiOPcs toward bacteria has been revealed. It is proposed that both OH and 1O2might be responsible for the observed bactericidal effects. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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