Abstract
An organic molecule, (EtO)3Si(CH2)3NH(CO)NH–(CH2)12–NH(CO)NH(CH2)3Si(OEt)3, combining urea functionalities and a 12-carbon alkyl chain, underwent sol–gel reactions in the presence of an acid catalyst, a large excess of water and variable amounts of EuCl3, giving rise to the formation of crystalline hybrids through a self-directed organization process in which hydrogen bonding interactions play a key role. Three photoluminescent lamellar Eu3+-doped silsesquioxane hybrids incorporating 1.01, 1.83 and 15.04% Eu3+ were prepared and fully characterized. The lamellar hybrids are room temperature multi-wavelength emitters due to the convolution of the hybrid's emitting centres and the Eu3+ intra-4f6 transitions. Their emission colour can be easily tuned along the Commission Internationale d'Eclairage chromaticity diagram from the bluish-purple region to the pink area, either by changing the excitation wavelength or the Eu3+ amount. The Eu3+ first coordination shell is very similar for the three photoluminescent lamellar Eu3+-doped silsesquioxane hybrids incorporating oxygen atoms of the carbonyl group, Cl atoms and water molecules, despite the minor variations found in the 5D0 quantum efficiency (16.3–19.2), number of water molecules (1.7–2.0) and experimental intensity 2 parameter (8.9–10.1 × 10-20 cm2) with the increase of Eu3+ content.