Oxygen Quantification Based on the Persistent Phosphorescence Lifetime of Host–Guest Nanocrystals

Oxygen responsiveness of the persistent phosphorescence lifetime is important for realizing rapid and highly accurate two-dimensional oxygen concentration mapping. Herein, we report a highly improved method for quantifying the oxygen concentration based on the persistent phosphorescence lifetimes of a crystalline material. Bulk crystals of 4,4′-di-tert-butylbenzophenone (DBBP) doped with deuterated dibenzo­[g,p]­chrysene are non-oxygen responsive and show persistent red phosphorescence with a lifetime of 2 s. However, nanocrystals of the same material show a decrease in phosphorescence decay time with increasing oxygen concentration while maintaining a curve resembling a single exponential. Consequently, oxygen concentrations from 0 to 160 mmHg can be reliably determined using phosphorescence lifetimes over 100 ms. Analysis of individual nanocrystals suggested that this wide range of oxygen quantification is possible owing to the limited one-dimensional oxygen permeability caused by the crystalline packing of the DBBP host.