Anion/cation induced optical switches based on luminescent lanthanide (Tb ³⁺ and Eu ³⁺) hydrogels

Two novel silica based lanthanide complexes (Tb(a) ₂ and Eu(a) ₂) were encapsulated into poly(acrylic acid) host. Both Tb(III) and Eu(III) containing hydrogels have typical and easily distinguished narrow line emissions occurring in the green and red region respectively. Particularly, the excitation wavelength for Eu complex can be extended into nearly visible light range (λ _ex = 395 nm). Interestingly, we discover that these target materials not only exhibit selective emission response towards HSO ₄ ^- (detection limit 10 ^-5 m) compared with CH ₃COO ^-, F ^-, Cl ^-, Br ^- and I ^- but also give unique quenching to Cu ²⁺ (detection limit 10 ^-5 m) (tested cations: Cu ²⁺, Pd ²⁺, Cd ²⁺, Co ²⁺ and Mn ²⁺). More importantly, this kind of materials can be recycled more than 10 times. Two novel Tb(III) and Eu(III) containing hydrogels were designed and have typical and easily distinguished narrow line emissions in the green and red region, respectively. In particular, the excitation wavelength for Eu complex can be extended into nearly visible light range (λ _ex = 395 nm). Interestingly, we discover that these target materials not only exhibit selective emission response towards HSO ₄ ^-, but also give unique quenching to Cu ²⁺.