White-light-emitting Ln-hydrogels with multi-stimuli responsiveness and applications in environmental sensing and anti-counterfeiting.

The construction of smart materials, especially white light emitting (WLE) hydrogels with multi-stimuli responsive properties, has received widespread attention from researchers. In this study, a WLE hydrogel was obtained by the doping of Eu and Tb into a blue emission low molecular weight gelator (MPF). Remarkably, the prepared WLE hydrogel possessed excellent stimuli responsiveness to pH, temperature and chemicals, and could be used as a soft thermometer and a selective sensor for Cu. The correlated color temperature of the WLE hydrogel was calculated to be 5063 K, suggesting a potential application in cool white light. Moreover, a series of metallohydrogels with different colors were obtained by modulating the ratio of MPF, Eu and Tb or changing the excitation wavelength, which was an excellent candidate to construct soft materials of a full-color system. Additionally, the WLE hydrogel could be used for constructing anti-counterfeiting materials. Therefore, this study provides a new approach for preparing smart WLE hydrogels with multiple functions.