5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

• Autor(a) principal: Paulo,Tercio de F.
• Data de Publicação: 2008
• Outros Autores: Silva,Maria A. S. da, Pinheiro,Solange de O., Meyer,Emerson, Pinheiro,Lucidalva S., Freire,José A., Tanaka,Auro A., Lima Neto,Pedro de, Moreira,Ícaro de S., Diógenes,Izaura C. N.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532008000400015
• topic: oxadiazole; thiol; SAMs; STM; kinetic of adsorption; Cyt c

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) spontaneously adsorbs on gold forming SAMs (self-assembled monolayers) that, based on STM (Scanning Tunneling Microscopy) and electrochemical data, contain pinholes through which [Fe(CN)6]4- and [Ru(NH3)6]3+ probe molecules access the underlying gold electrode. For the former molecule, the dependence of the faradaic current on the electrolyte solution pH value allowed the evaluation of the surface pKa as 4.2. The thermodynamic parameters DHads and DGads for the Hpyt adsorption process could be described by the Langmuir model and were calculated as -20.01 and -39.39 kJ mol-1, respectively. Electrodic redox reaction of cytochrome c metalloprotein was accessed by using the Hpyt SAM with a heterogeneous electron transfer rate constant of 2.29 × 10-3 cm s-1.