Singlet oxygen produced by quasi-continuous photo-excitation of hypericin in dimethyl-sulfoxide

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• 作者：J. Varchola^a ; K. Želonkov&aacute ; ^a ; D. Chorvat Jr^b ; D. Jancura^a ; ^c ; P. Miskovsky^a ; ^b ; ^c ; G. B&aacute ; nó ; ^a ; ^c ; ^{gregor.bano@upjs.sk" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Singlet oxygen ; Hypericin ; Photosensitizer ; Dimethyl-sulfoxide
• 刊名：Journal of Luminescence
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：177
• 期：Complete
• 页码：17-21
• 全文大小：854 K

文摘

Singlet oxygen (O₂(¹Δ_g)) production by photo-excited hypericin (Hyp) dissolved in dimethyl-sulfoxide (DMSO) was studied by means of time-resolved phosphorescence measurements. In order to minimize photo-bleaching, the samples were excited in quasi-continuous mode using long-pulse (35 μs) laser excitation. The measured lifetime of singlet oxygen is τ_Δ=5.5±0.3 μs. This result helps to resolve the discrepancy existing in the literature concerning singlet oxygen lifetime in DMSO. The obtained quantum yield of singlet oxygen photosensitized by Hyp in air-saturated DMSO is Φ_Δ=0.4±0.03. The rate constant for Hyp triplet state depopulation in reaction with ground state molecular oxygen is measured to be k_q=1.6±0.3×10⁹ M⁻¹ s⁻¹.