Lanthanide-Boosted Singlet Oxygen from Diverse Photosensitizers along with Potent Photocatalytic Oxidation

Singlet oxygen (1O2) plays a central role in photochemical and photobiological research. Although many photosensitizers for efficient 1O2 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 (Ln3+), 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 1O2 emission of carbon dots and rose bengal was enhanced 4 times in the presence of Ce3+. Some nonphosphorescent, but strongly fluorescent dyes that are not known as photosensitizers can still be mediated by Ln3+ to produce 1O2, but metal-chelating calcein was not enhanced. F...