Highly luminescent di-ureasil hybrid doped with a Eu(III) complex including dipicolinate ligands

A short chain di-urea cross-linked poly(oxyethylene) (POE)/siloxane hybrid host (di-ureasil), designated as d-U(600), was doped with the Na-3[Eu(dipic)(s)]center dot xH(2)O (where dipic(2-) is the dipicolinate ion) complex. The resulting material is non-porous, semi-crystalline and thermally stable up to 145 degrees C. Because of the presence of the bulky dipic(2-) ligands, the addition of the complex to d-U(600) leads to the partial destruction of the hydrogen-bonded POE/urea aggregates of the hybrid matrix and to the formation of extra urea/urea aggregates. The incorporation of the complex into d-U(600) accounts for an increase of both the D-5(0) lifetime and quantum efficiency values (1.950 +/- 0.007 ms and 0.50, respectively) with respect to those of the isolated complex (1.7 ms and 0.46, respectively). The addition of the complex also contributes to an enhancement of the absolute emission quantum yield value, whose maximum value (0.66 excited at 280 nm) is the highest value reported for organic-inorganic hybrids modified by lanthanide complexes. (C) 2009 Elsevier B.V. All rights reserved.