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 C3 -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 pKa (<5) from those with higher pKa (>9).