Synthesis and Luminescence Properties of Immobilized Europium β-CD Complexes on Silica

Abstract

Functionalized silica gel organic–inorganic hybrid materials based on covalently grafted lanthanide coordinations onto organosilicone have been the subject of intense study due to their superior physicochemical properties. However, it cannot be assumed that all the primary guest molecules can be directly covalent-grafted onto the host that prevents H₂O molecules from coordinating with the central ion; the introduction of a medium could be useful in this regard. In the present work, a medium β-cyclodextrin (β-CD) was employed, and by sol–gel and molecular assembly processes, immobilization of a europium–β-CD inclusion on silica and the preparation of a novel fluorescent polymeric hybrid material β-CD–TESPIC–TTA–Eu were achieved. This research shows that β-CD can prevent the H₂O molecules from coordinating with the central ion Eu³⁺ (inclusion). The novel hybrid material has an amorphous and homogeneous network surface and exhibits excellent film-forming properties, bright-red light emission that is dominated by the ⁵D₀ → ⁷F₂ transition of Eu³⁺, and a lifetime of 0.44 ms.