Efficient luminescent materials made by incorporation of terbium(III) and 2,2-bipyridine in silica/poly(ethylene oxide) hybrid gels

Silica/poly(ethylene oxide) hybrid gels have been prepared by the sol–gel method using a precursor synthesized by reacting 3-isocyanotriethoxysilane with O,O′-bis(2-aminopropyl)-poly(ethylene oxide). The hybrid gels were consecutively swelled in ethanolic solutions first of terbium nitrate and then of 2,2-bipyridine and in this manner they absorbed important amounts of both lanthanide ions and the ligand. The result was an efficient luminescent material producing bright green luminescence by UV excitation. The ligand then acts as an antenna for the exciting radiation which is transferred to the lanthanide emitter. The hybrid material can also yield blue luminescence by itself, which is much enhanced in the presence of terbium ions.