Brilliant yellow dye immobilized on silica and silica/titania based hybrid xerogels containing bridged positively charged 1,4-diazoniabicyclo[2.2.2]octane: Preparation, characterization and electrochemical properties study

Silica and silica/titania based hybrid xerogels containing the double charged 1,4-diazoniabicyclo[2.2.2]octane group bonded in a bridged way were obtained. The hybrids were characterized by infrared spectroscopy and CHN analyses for the identification and determination of organic content. N(2) adsorption-desorption isotherms and SEM were applied to study morphological and textural aspects. The hybrid materials presented anion-exchange properties that allowed their use as adsorbent for brilliant yellow anionic dye. These modified materials were used to prepare carbon paste electrodes for cyclic voltammetric measurements, where the brilliant yellow, for the first time, was applied as electroactive species. The pH solution has no effect on the anodic peak potential and anodic peak current in the values range between 2.0 and 7.0. The electrode response was invariant under various oxidation-reduction cycles showing that the system is chemically very stable. Considering that the presence of titanium oxide in the xerogel enhanced the conductivity, a carbon paste electrode of the (R(2)dabco)BY/SiO(2)/TiO(2) material was prepared to study the electrocatalytic oxidation of ascorbic acid by cyclic voltammetric and chronoamperometric techniques. (C) 2007 Elsevier Inc. All rights reserved.