Laboratory of Optical Processes in Nanostructured Materials, National Institute of Materials Physics, Atomistilor Street 405A, MG-7, 077125 Bucharest, Romania.
Interdisciplinary School of Doctoral Studies, University of Bucharest, Șoseaua Panduri 90, 050663 Bucharest, Romania.
Int J Mol Sci. 2022 Apr 2;23(7):3975. doi: 10.3390/ijms23073975.
The effect of sodium thiosulfate (ST) on the photodegradation of azathioprine (AZA) was analyzed by UV-VIS spectroscopy, photoluminescence (PL), FTIR spectroscopy, Raman scattering, X-ray photoelectron (XPS) spectroscopy, thermogravimetry (TG) and mass spectrometry (MS). The PL studies highlighted that as the ST concentration increased from 25 wt.% to 75 wt.% in the AZA:ST mixture, the emission band of AZA gradual downshifted to 553, 542 and 530 nm. The photodegradation process of AZA:ST induced: (i) the emergence of a new band in the 320-400 nm range in the UV-VIS spectra of AZA and (ii) a change in the intensity ratio of the photoluminescence excitation (PLE) bands in the 280-335 and 335-430 nm spectral ranges. These changes suggest the emergence of new compounds during the photo-oxidation reaction of AZA with ST. The invoked photodegradation compounds were confirmed by studies of the Raman scattering, the FTIR spectroscopy and XPS spectroscopy through: (i) the downshift of the IR band of AZA from 1336 cm to 1331 cm, attributed to N-C-N deformation in the purine ring; (ii) the change in the intensity ratio of the Raman lines peaking at 1305 cm and 1330 cm from 3.45 to 4.57, as the weight of ST in the AZA:ST mixture mass increased; and (iii) the emergence of a new band in the XPS O1s spectrum peaking at 531 eV, which was associated with the C=O bond. Through correlated studies of TG-MS, the main key fragments of ST-reacted AZA are reported.
采用紫外可见分光光度法、光致发光（PL）、傅里叶变换红外光谱（FTIR）、拉曼散射、X 射线光电子能谱（XPS）、热重分析（TG）和质谱（MS）分析了硫代硫酸钠（ST）对巯嘌呤（AZA）光降解的影响。PL 研究表明，随着 ST 在 AZA:ST 混合物中浓度从 25wt.%增加到 75wt.%，AZA 的发射带逐渐蓝移至 553、542 和 530nm。AZA:ST 诱导的光降解过程导致：（i）在 AZA 的紫外可见光谱中 320-400nm 范围内出现新带；（ii）在 280-335nm 和 335-430nm 光谱范围内的光致发光激发（PLE）带的强度比发生变化。这些变化表明，在 AZA 与 ST 的光氧化反应过程中出现了新的化合物。通过拉曼散射、FTIR 光谱和 XPS 光谱的研究，证实了所提出的光降解化合物的存在，这些研究通过以下几点证实：（i）AZA 的 IR 带从 1336cm 蓝移至 1331cm，归因于嘌呤环中 N-C-N 变形；（ii）随着 AZA:ST 混合物中 ST 质量的增加，在 1305cm 和 1330cm 处的拉曼线的强度比从 3.45 变为 4.57；（iii）在 XPS O1s 光谱中出现一个新的峰，位于 531eV，与 C=O 键有关。通过 TG-MS 的相关研究，报道了 ST 反应的 AZA 的主要关键片段。
