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Updated: Jun 4, 2026

Time-resolved Photophysical Characterization of Triplet-harvesting Organic Compounds at an Oxygen-free Environment Using an iCCD Camera
Published on: December 27, 2018
Direct observation and quantitative characterization of singlet oxygen in aqueous solution upon UVA excitation of
Yazhou Zhang1, Xianchun Zhu, Joshua Smith
1Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, USA.
Abstract:
The incorporation of 6-thioguanine (6-TG) into DNA increases the risk of (1)O(2)-initiated skin cancer. We herein provide the first report on quantitative characterization of the photoactivity of 6-thioguanines including 6-TG and 6-thioguanosine. Time-resolved singlet oxygen luminescence was observed directly for the first time after UVA irradiation of 6-thioguanines in both CHCN(3) and aqueous solutions. Their photosensitization was characterized by the quantum yield of singlet oxygen production, showing a dramatic decrease over time from the initial 0.49-0.58 to zero. Experiments performed on both 6-TG and 6-thioguanosine did not show any significant difference in the quantum yield of singlet oxygen production, indicating that there was no potential participation of 7H- and 9H-tautomers. Our findings provide a primary basis for a better understanding of molecular events of thiopurine drugs in biological systems.
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