Luminescence enhancement of Ln3+-β-diketonate complexes confined in zeolite aqueous suspension by 3-Aminopropyltriethoxysilane

Highlights: • A strategy to use APTES as a stopper to plug up the pores of the zeolite was achieved. • The encapsulated Ln³⁺-β-diketonate complexes in zeolite was highly luminescence. • The Ln³⁺-β-diketonate complexes in zeolite was highly waterproof. • The emission of the Ln³⁺-β-diketonate complexes in zeolite was tunable. • Strongly luminescent films with tunable emission were prepared. -- Abstract: Encapsulation of lanthanide complexes within the pores of zeolites can lead to interesting luminescent composite. However, the luminescence quenching caused by water molecules and increased proton strength inside the pore under aqueous conditions limit the applications of the materials in aqueous solution and wet conditions. Making them be suitable for application in aqueous environment still remains a big challenge. Herein we developed a simple, cost-effective, less time-consuming and environmentally friendly strategy to make the luminescent composite retain their high luminescence even dispersed in aqueous solution for a long time by simply modifying them with 3-Aminopropyltriethoxysilane (APTES) under aqueous conditions. The APTES attached to zeolite Y (ZY) dispersed in water can remarkably enhance the luminescence of confined Ln³⁺-β-diketonate complexes and can also make them highly waterproof. The mechanism responsible for the luminescence enhancement and the waterproofness is that the presence of APTES can neutralize the acidic sites thus favoring the formation of lanthanide complexes with higher coordination number and can prevent water molecules from entering the pores of ZY. Highly luminescent aqueous suspension of composite with tunable emitting color were therefore achieved by varying the Eu³⁺/Tb³⁺ molar ratio, and strongly luminescent films were therefore prepared by incorporating the composite into PVA polymer from aqueous solution.