Department of Chemistry , Waterloo Institute for Nanotechnology , Waterloo , Ontario , Canada N2L 3G1.
Analytical & Testing Center, College of Chemistry, State Key Laboratory of Hydraulics and Mountain River Engineering , Sichuan University , Chengdu 610064 , China.
ACS Nano. 2019 Dec 24;13(12):14152-14161. doi: 10.1021/acsnano.9b06840. Epub 2019 Dec 4.
Singlet oxygen (O) plays a central role in photochemical and photobiological research. Although many photosensitizers for efficient O generation were reported, further improving its yield and oxidation power is still highly desirable. Instead of developing new ones, current photosensitizers might be boosted by mediators to facilitate energy transfer. Taking advantage of the long triplet state lifetime of lanthanide ions (Ln), we herein demonstrate their roles as potent oxidation mediators. Using oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) at neutral pH as a difficult model reaction, based on the fluorescence, phosphorescence, and metal-binding properties, various dyes and nanomaterials were classified into four types. The O emission of carbon dots and rose bengal was enhanced 4 times in the presence of Ce. Some nonphosphorescent, but strongly fluorescent dyes that are not known as photosensitizers can still be mediated by Ln to produce O, but metal-chelating calcein was not enhanced. Finally, nonemissive dyes failed to show activity. As mediators, the excited Ln can migrate a long distance and transfer energy to O, resulting in high O yield. Since redox-active Ce and Eu had the highest activity, participation of oxidation involving excited lanthanides might be possible too. In addition, Ln also enhanced the activity of graphene quantum dots, graphene oxide, and -CN. Rapid degradation of organic dyes was demonstrated, further supporting a high photocatalytic activity of the Ln-mediated system.
单线态氧 (O) 在光化学和光生物学研究中起着核心作用。尽管已经报道了许多用于高效产生 O 的光敏剂，但进一步提高其产率和氧化能力仍然是非常需要的。与其开发新的光敏剂，不如通过介体来增强现有的光敏剂，以促进能量转移。利用镧系离子 (Ln) 的长三重态寿命，我们在此证明了它们作为有效氧化介体的作用。以中性 pH 下 3,3',5,5'-四甲基联苯胺 (TMB) 的氧化作为困难的模型反应，根据荧光、磷光和金属结合特性，将各种染料和纳米材料分为四类。Ce 的存在将碳点和玫瑰红 Bengal 的 O 发射增强了 4 倍。一些非磷光但强荧光的染料，尽管不是已知的光敏剂，但仍可以被 Ln 介体产生 O，但金属螯合钙黄绿素没有增强。最后，非发射性染料没有显示出活性。作为介体，激发的 Ln 可以迁移很长的距离并将能量转移给 O，从而产生高的 O 产率。由于具有氧化还原活性的 Ce 和 Eu 具有最高的活性，因此可能也涉及到激发态镧系元素的氧化参与。此外，Ln 还增强了石墨烯量子点、氧化石墨烯和 -CN 的活性。有机染料的快速降解得到了证明，进一步支持了 Ln 介导体系的高光催化活性。
