MODIFIED ELECTRODES FROM ORGANIC-INORGANIC HYBRID GELS FORMED BY HYDROLYSIS-POLYCONDENSATION OF SOME TRIMETHOXYSILYLFERROCENES

Gels formed from trimethoxysilylferrocene 1 and 1,1'-bis(trimethoxysil yl)ferrocene 2 copolymerized with tetramethoxysilane have been deposit ed onto platinum, and allow the building of modified electrodes with i nteresting electrochemical properties. The electrochemical response of the gels has been found to be strongly dependent on the starting mole cule and its concentration, but only weakly on the electrolyte nature. Special attention has been paid to the dynamics of the electron trans fer through the gels, and a quantitative analysis has been performed i n various cases. While the gels prepared from the disilylated ferrocen e 2 display, like several different functionalized polymers, a Cottrel lian diffusion of the charge transfer (in accordance with the classica l theoretical treatment of Andrieux and Saveant), in the gels formed f rom the monosilylated ferrocene 1, the charge transfer follows a power law with a fractional exponent. This unique behaviour is indicative o f a particular substructure in the gels, with the ferrocene moieties p robably positioned at the surface of accessible silica particles.