Electron transfer rates of alkyl-ferrocene molecules forming incomplete monolayer on silicon electrodes

• G RIVEROS ^[1] ; S MENESES ^[2] ; S ESCOBAR ^[2] ; C GARÍN ^[1] ; B CHORNIK ^[3]
  1. [1] Universidad de Valparaíso

     Universidad de Valparaíso

     Valparaíso, Chile

     
  2. [2] Pontificia Universidad Católica de Valparaíso

     Pontificia Universidad Católica de Valparaíso

     Valparaíso, Chile

     
  3. [3] Universidad de Chile

     Universidad de Chile

     Santiago, Chile

     

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• Localización: Journal of the Chilean Chemical Society (Boletín de la Sociedad Chilena de Química), ISSN-e 0717-6309, ISSN 0366-1644, Vol. 55, Nº. 1, 2010, págs. 61-66
• Idioma: inglés
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  • This study shows the results obtained when binding alkyl ferrocene molecules on silicon surface forming incomplete monolayers. The electrodic surface functionalization is carried out by a two step procedure: First, a hydrosilytation reaction between a Si-H surface and an alkenyl bromide active by white light; and then, the reaction of this surface with a monolithio ferrocene solution. Alkenyl bromide with different numbers of carbon atoms (3, 5 and 10 carbon atoms) were employed in order to obtain propyl, pentyl and decyl ferrocene chains on the electrodic surface. The samples of modified silicon were analyzed by X-ray photoelectron spectroscopy (XPS) and electrochemical measurements confirmingthe presence of ferrocene molecules onthe electrode surface. The results obtained show that in each and every case, there were incomplete monolayers on the silicon surface, ranging from 16% to 42 %, depending on the alkenyl bromide employed in the synthesis. AC voltammetry was employed to determine the kinetic of the eletron transfer between ferrocene molecules and the silicon electrode. However, therate constant is not influenced by the lengthofthe alkyl chain, and is usually constant (2.01 s-1-3.66 s-1). The result above is due to the eletron transfer process which is determine by eletron hopping in a regime of bonded diffusion and not by a long-rate eletron transfer such as in a full compact monolayer.