Multicolor Tunable AIE Fluorescent Hydrogels Containing Europium Ionic Complexes via the “One-Pot Method”

The coordination of multiple luminescent centers in a simple and efficient way is a difficult challenge for realizing the tunable multicolor function of fluorescent hydrogels. In this work, we synthesized a fluorescent hydrogel with multicolor conversion via a “one-pot method,” which greatly simplifies the tedious steps of preparing fluorescent hydrogels. The luminescence intensity and color of the synthesized DPA-Eu/TPE@PVA hydrogel can be modulated by various stimuli, such as the excitation wavelength, pH, and presence of Fe³⁺ ions. The entire work centers on the rational introduction of the light-emitting molecule tetrakis(4-hydroxyphenyl)ethylene (TPE-4OH) and the lanthanide ionic complex 2,6-pyridinedicarboxylic acid-Eu (DPA-Eu) into the poly(vinyl alcohol) (PVA) polymer network. Since the luminescence mechanisms of these two molecules differ, with the former emitting light with the aid of the aggregation-induced emission (AIE) effect and the latter emitting light through energy transfer via metal dynamic coordination bonds, individual luminescent molecules can be controlled independently under specific stimuli. The realization of this tunable multicolor fluorescence function has contributed to its application in fields such as sensors, probes, and information encryption.