Triplet Formation of 4-Thiothymidine and Its Photosensitization to Oxygen Studied by Time-Resolved Thermal Lensing Technique

Harada, Y; Suzuki, T; Ichimura, T and Xu, YZ (2007). Triplet Formation of 4-Thiothymidine and Its Photosensitization to Oxygen Studied by Time-Resolved Thermal Lensing Technique. Journal of Physical Chemistry B, 111(19) pp. 5518–5524.

DOI: https://doi.org/10.1021/jp0678094

Abstract

Excited-state dynamics of 4-thiothymidine (S4-TdR) and its photosensitization to molecular oxygen in solution with UVA irradiation were investigated. Absorption and emission spectra measurements revealed that UVA photolysis of S4-TdR gives rise to a population of T1(*), following S2(*) f S1(n*) internal conversion. In transient absorption measurement, the 355 nm laser photolysis gave broad absorption (380-600 nm) bands of triplet S4-TdR. The time-resolved thermal lensing (TRTL) signal of S4-TdR containing the thermal component due to decay of triplet S4-TdR was clearly observed by the 355 nm laser excitation. The quantum yield for S1 f T1 intersystem crossing was estimated to be unity by a triplet quenching experiment with potassium iodide. In the presence of molecular oxygen, the photosensitization from triplet S4-TdR gave rise to singlet oxygen O2 (1g) with a quantum yield of 0.50. Therapeutic implications of such singlet oxygen formation are discussed.

Viewing alternatives

Metrics

Public Attention

Altmetrics from Altmetric

Number of Citations

Citations from Dimensions

Item Actions

Export

Recommendations