Photochemically Deoxygenating Media For Protection Of Phosphorescent Materials

In general,phosphorescence is easily quenched by oxygen and it can be observed under oxygen-free environment.Phosphorescence can be applied in bioimaging,oxygen sensors and OLEDs.However,due to the ubiquity of oxygen,there are many difficulties in the application of phosphorescence.Based on the previous experimental results,we find that NMP,NMO,DMI,DMSO,DMPU,PVP has ability to photoactivate phosphorescence.Dissolving phosphorescent compounds in these media and ilumination the solution by UV flash lamp,it can be observed that the phosphorescence could be gradually enhanced under aerated condition.Further,the mechanism behind this photochemical deoxygenation is explored through a series of characterization methods.We think currently that during the photoactivated process,the phosphorescence produced by the phosphorescent compound interacts with the molecular oxygen in the solvent initially to form singlet oxygen,while the solvent interacts with the singlet oxygen in the solution to consume the singlet oxygen.After confirming that these medias can do photochemical deoxygenation,further exploration of applications based on this particular property is under way.This photoactivated system can apply to record the history of illumination because the oxygen can be clean after photoirradiation and then phosphorescence will arise from the solution or gel by irradiation of UV lamp.Except that PVP is a solid powder at room temperature,the rest are all liquids.PVP can be dissolved in DCM,water and methanol,and forms a gel as the solvent evaporates.In the gel formed by PVP,Up to 12% upconversion quantum efficiency can be achieved by direct laser excitation under air conditions.The gel can be used to measure the spectra of transient absorption,time-resolved emission and Stern-Volmer plot.