Toward Luminescent Composites by Phase Transfer of SrF₂ : Eu³⁺ Nanoparticles Capped with Hydrophobic Antenna Ligands

Abstract Transparent dispersions of hydrophobic SrF₂ : Eu³⁺ nanoparticles in cyclohexane with up to 20% europium were obtained by fluorolytic sol‐gel synthesis followed by phase transfer into cyclohexane through capping with sodium dodecylbenzenesulfonate (SDBS). The particles were characterized by TEM, XRD and DLS as spherical objects with a diameter between 6 and 11 nm in dry state. ¹H‐¹³CP MAS NMR experiments revealed the binding of the anionic sulfonate head group to the particle surface. The particles show bright red luminescence upon excitation of the aromatic capping agents, acting as antennas for an energy transfer from the benzenesulfonate unit to the Eu³⁺ centers in the particles. This synthesis method overcomes the current obstacle of the fluorolytic sol‐gel synthesis that transparent dispersions can be obtained directly only in hydrophilic solvents. To demonstrate the potential of such hydrophobized alkaline‐earth fluoride particles, transparent luminescent organic‐inorganic composites with 10% SrF₂ : Eu³⁺ embedded into polyTEGDMA, polyBMA, polyBDDMA and polyD3MA, respectively, were prepared, endowing the polymers with the luminescence features of the nanoparticles.