Electrode modification with thin films of amine functionalized mesoporous silica molecular sieves

Highly ordered thin films of an amine functionalized mesoporous silica molecular sieve were prepared on conductive tin-doped indium oxide substrates by one-step dip-coating from a mixture containing tetraethyl- orthosilicate as the silica source, the non-ionic surfactant Brij-56 as the structure-directing agent and (3-aminopropyl)triethoxysilane. The surfactant was removed by calcination.;The use of conductive tin-doped indium oxide slides as substrates allowed the dip-coated films to be used directly as working electrodes. The cyclic voltammetry responses of the anion [Fe(CN)6]3- and of the cations [RU(bPY)3]2+, [Ru(NH3) 6]2+ and cis-[Ru(bpy)2(H2O) 2]2+ in different pH electrolytes of films containing the amine side chains were compared with those obtained with pure silica mesoporous films containing no amine side chains. The coupling of ferrocenecarboxylic acid with the amine side chains in the functionalized mesoporous thin film modified electrodes was also investigated.;The TEM and ED showed that the films calcined at high temperatures (≥ 350°C) contained highly ordered pores with a face centered cubic structure. When lower calcination temperatures (≤ 275°C) were used, the films had a primitive cubic structure. The nitrogen adsorption-desorption isotherms of the materials showed narrow pore size distributions and large surface areas. ATR-FTIR spectra showed that amine groups were still present in the films after calcination a ≤ 2750C. This was also confirmed by 29Si solid-state MAS/NMR. From the elemental analysis, the loading of the amine functional groups was ∼1.3mmol/g.