Efficient conversion of arylene precursors into photoluminescent phosphonates for surface modification of metal oxides

Abstract

Three highly fluorescent phosphonates have been prepared in good yields from different arylene bridged 5-iodothiophenes by following an optimized four-step procedure. The compounds have been immobilised on mesoporous zirconia, alumina and titania particles in order to probe their luminescence properties on the surfaces. The organic compounds as well as the obtained hybrid materials have been characterised using liquid phase or MAS NMR spectroscopy, N₂ physisorption measurements, ATR-IR spectroscopy and elemental analysis. The luminescence intensity of the organic molecules was found to be in general much more dependent on the surface used for grafting rather than on the dye loading obtained for different metal oxides powders. The luminescence extinction, which has been detected for all coated TiO₂ samples, is most likely due to the different electronic properties of this semiconducting support compared to the other surfaces. The method described shows how fluorescent tracers can be easily synthesised and applied in surface analytics after exploring the interaction of the corresponding organophosphonates with several ceramic interfaces.