New sensing devices part 1:: indole-containing polyamines supported in nanosized boehmite particles

The synthesis, characterisation and optical properties of new sensing systems made by attaching different polyamine chains functionalised with an indole fluorophore to a boehmite matrix is reported for the first time. Firstly, a family of tri(alkoxy)alkylpolyaminosilanes have been reacted with indole-3-carboxaldehyde to form the corresponding Schiff bases which were reduced with sodium borohydride. The anchoring to the surface of the boehmite nanoparticles was carried out by reacting the precursors with the hydroxyl groups available in the surface of the support. The characterisation of the materials by elemental microanalysis, X-ray powder diffraction, CP-MAS Si-29 NMR and electron microscopy unambiguously proved that covalent anchorage had occurred. Steady-state fluorescence emission studies showed that these materials present a very efficient sensing behaviour for hydrogen ions, metal ions such as Cu2+ and Zn2+ and for the anionic nucleotides ATP, ADP and AMP.