An Interfacial Europium Complex on SiO(2) Nanoparticles: Reduction-Induced Blue Emission System

In this study, Eu-coated SiO(2) nanoparticles have been prepared, consisting of an interfacial complex of Eu and 1,10-phenanthroline (phen) at the solid surfaces of the SiO(2)/Eu nanostructures. The as-prepared SiO(2)/Eu/phen nanoparticles exhibits sharp red emission via energy transfer from the phen to the Eu(III). After sintering at 200 °C in air, the emission is tuned from red to blue. The blue emission is originated from Eu(II). This reduction-induced emissive phenomenon resulted from the electron-donating environment created by the surrounding phen and SiO(2), which is the first reported fabrication of a stable Eu(II)-based emissive material using mild conditions (reaction in air and at low temperature) and an organic-inorganic hybrid nanostructure. The existence of two different stable oxidation states with characteristic emissions, blue emissive Eu(II) and red emissive Eu(III), suggests significant potential applications as novel luminescent materials with inorganic-organic hybrid structures.