Constructing [2.2]Paracyclophane-Based Ultrasensitive Optical Fluorescent-Phosphorescent Thermometer with Cucurbit[8]uril Supramolecular Assembly

The pursuit of developing novel approaches to fully organic and efficient phosphorescent materials is in high demand. The optical activity of such functional, organic phosphorescent/fluorescent materials may exhibit great temperature dependence, allowing their application as advanced, highly sensitive molecular thermometers. In this study, a rational strategy involving host-guest complexation and polymerization of [2.2]paracyclophane (PCP) based molecules with cucurbit[8]uril (CB8) to suppress the molecular motion and promote temperature-dependent phosphorescence is presented. The rigid cavity of CB8 provides an ideal microenvironment to host PCP molecules 1 and 2, significantly enhancing the photophysical performance after complexation. Co-polymerizing phosphors 1 and 2 with acrylamide is an efficient method for improving phosphorescence. Incorporating CB8 into the resulting P-1 and P-2 polymers enhances phosphorescence performance. Importantly, the obtained materials exhibit a big structure-dependent spectral shift and change of phosphorescence lifetimes with temperature, allowing novel, phosphorescence-based, and purely organic optical thermometers to be developed. The practical applications of PCP-based luminescent materials in temperature sensing via a multi-parameter approach are showcased, i.e., using fluorescence spectral shift and changes in bandwidth, as well as phosphorescence lifetimes, exhibiting thermal sensitivity of approximate to 17.7 cm(-1) degrees C-1, 47.8 cm(-1) degrees C, and 5.2% degrees C-1, respectively.