Multistep Anchoring Route of Luminescent (5-Amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III) on Si(100)

A multistep route for the covalent anchoring of (5-amino-1,10-phenanthroline)tris(dibenzoylmethane)europium(III) molecules on silicon (100) has been developed. The anchoring route consists of Si functionalization with N-hydroxysuccinimide (NHS) activated carboxylic acid, followed by nucleophilic substitution at the carboxylic acid sites. Characterization of the resulting Si based hybrid materials was achieved by using several complementary techniques: X-ray photoelectron spectroscopy (XPS), attenuated total reflection FTIR spectroscopy (ATR-FTIR), AFM and fluorescence spectroscopy. Comparison of results obtained for NHS activated Si surfaces with those of inert alkyl functionalized Si surfaces proved the covalent anchoring of the Eu complex and ruled out the presence of physisorbed Eu species. The 1.8 nm thickness of the grafted layer, estimated by atomic-force lithography, is compatible with the presence of the anchored complex on the surface. Fluorescence measurements proved that luminescence properties are retained in the grafted complex.