Lanthanide(III)‐Based Multicolor Luminescent Hybrid Gel for Amine Sensing

Bridged polysilsesquioxanes (BPs) show great potential in the development of lanthanide‐based luminescent materials, owing to their capacity to loading lanthanide complexes with high concentration and their flexible processability. A novel BP precursor, consisting of a C ₃‐symmetrical benzene central core moiety, capable of sensitizing the luminescence of Eu³⁺ and Tb³⁺ is reported. Tunable, full‐color luminescent gels were facilely prepared by mixing the as‐synthesized precursor and Ln³⁺ ions in appropriate solvents. By either changing the Eu³⁺/Tb³⁺ molar ratio or altering the excitation wavelength, the emission colors of the final gels can be finely tuned. Additionally, the yellow‐colored emissive gel with a molar ratio of Eu³⁺ to Tb³⁺ of 0.5 can be used as an effective ratiometric luminescent sensor for distinguishing amines with lower pK _a (<5) from those with higher pK _a (>9).