Highly luminescent europium(iii) complexes containing organosilyl 4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dionate ligands grafted on silica nanoparticles

Abstract

A novel organic–inorganic mesoporous luminescent hybrid material was designed by linking a ternary Eu³⁺ complex to the functionalized hexagonal mesoporous MCM-41 with the modified β-diketone, 4,4,5,5,5-pentafluoro-1-(naphthalen-2-yl)pentane-1,3-dione (HPFNP), which contains a polyfluorinated alkyl group as well as the long conjugated naphthyl group. β-Diketone grafted to the coupling agent 3-(triethoxysilyl)propylisocyanate was used as the precursor for the preparation of mesoporous materials. MCM-41, consisting of ternary complex, Eu(PFNP-Si)₃(bath) covalently bonded to the silica-based network, which was designated as Eu(PFNP-Si)₃(bath)/MCM-41, was obtained by interacting europium nitrate, SiPFNP-Na and 4,7-diphenyl-1,10-phenanthroline (bath) into the mesoporous material via a ligand-exchange reaction. The synthesized luminescent hybrid material was fully characterized by various spectroscopic techniques, and its photophysical properties were investigated. Eu(PFNP-Si)₃(bath)/MCM-41 exhibits an efficient intramolecular energy transfer process from the silylated β-diketone to the central Eu³⁺, namely, the “antenna effect”, which favoured highly luminescent behaviour in the modified hexagonal mesoporus silica.