Unique Property of Nontraditional Intrinsic Luminescence in the Transforming of Solution‐Hydrogel‐Solid and Its Applications

For the unusual phenomenon of nontraditional intrinsic luminescence, a systematic fluorescence study is conducted in the phase transformation from solution through hydrogel to solid states. In this process, significant differences are found in fluorescence intensity, peak position, lifetime, and excitation‐dependent emission. In particular, the samples in the hydrogel state show two fluorescent peaks at 480 and 516 nm, respectively, while only one fluorescent peak is detected in the cases of solution (at 516 nm) or solid (at around 450 nm). More interestingly, the longer wavelength peak presents excitation‐dependent fluorescence, and the shorter one is excitation‐independent. These unique fluorescent observations can be ascribed to the fact that the aggregates of amine groups act as the actual fluorescent centers, which are quite sensitive to their surrounding microenvironments. Based on these results, some simulation tests of sensors and intelligent hydrogels in response to water are also studied. For nontraditional intrinsic luminescence (NTIL), the fluorescent properties are systematically studied in the phase transformation from solution through hydrogel to solid. Significant differences are confirmed in fluorescence intensity, peak position, lifetime, and excitation‐dependent emission, possibly due to the fact that the aggregates of amine groups act as the actual fluorescent centers. Meanwhile, some stimulus‐responsive materials are prepared.