Water‐Soluble Luminescent Hybrid Composites Consisting of Oligosilsesquioxanes and Lanthanide Complexes and their Sensing Ability for Cu2+

Abstract Water‐soluble hybrid composites with great potential for selective and sensitive sensing and that are obtained through simple, rapid, and environmentally friendly methods are highly desirable and remain a challenging task. Herein, we present luminescent hybrid composites that were realized by linking Na 3 [Ln(dpa) 3 ] (dpa=2,6‐pyridinedicarboxylic acid) to octa‐amino functionalized polyhedral oligomeric silsesquioxane (POSS‐NH 2 ) through hydrogen‐bonding interactions between the oxygen atoms of the carboxylate groups of dpa and the hydrogen‐bond‐donor amino groups. The resulting hybrid composites Ln(dpa) 3 @POSS‐NH 2 are highly soluble in aqueous solutions and the quantum yield of Eu(dpa) 3 @POSS‐NH 2 is as high as 56.5 % or 46.3 % in the solid state and in aqueous solution, respectively, as determined by using the integrating sphere method. The novel water‐soluble luminescent hybrid composites exhibit high thermal and photostability, and the emitted colors of the resulting hybrid composite can be finely tuned by changing the Eu 3+ /Tb 3+ ratio. Interestingly, Eu(dpa) 3 @POSS‐NH 2 hybrid composites exhibited an effective switch‐off fluorescence response to Cu 2+ over other common metal ions in aqueous media.