O composto 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) adsorve espontaneamente sobre ouro formando SAMs ("Self-Assembled Monolayers") que, de acordo com os resultados eletroquímicos e de STM ("Scanning Tunneling Microscopy"), contêm poros através dos quais as moléculas dos complexos [Fe(CN) 6 ] 4-, a dependência da corrente faradáica com o pH da solução eletrolítica permitiu o cálculo do pKa da molécula de Hpyt adsorvida sobre ouro (4,2). Os parâmetros termodinâmicos, H ads and G ads , para o processo de adsorção desta molécula foram estimados em -20,01 e -39,39 kJ mol -1 , respectivamente, utilizando-se o modelo de Langmuir. O processo redox da metaloproteína citocromo c foi estudado utilizando-se a SAM de Hpyt. A constante de velocidade heterogênea de transferência de elétrons foi calculada em 2,29 10 -3 cm s -1 .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(NH 3 ) 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 H ads and G ads 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 .

Um novo derivado da piperazina, 5-oxopiperazinio-3-sulfonato monohidratado, foi produzido a partir de uma rota sintética simples como resultado da adição do íon bisulfito, HSO 3 -, ao anel e do ataque nucleofílico de moléculas de água a moléculas de pirazina. O material isolado foi caracterizado por RMN, espectrometria de massa, infravermelho e difração de raios-X.A new derivative of piperazine, 5-oxopiperazinium-3-sulfonate monohydrate, was produced from a simple synthetic route as a result of the nucleophilic addition to HSO 3 -bisulphite ion and of the nucleophilic attack of water molecules on pyrazine molecules. The isolated material was characterized by means of NMR, mass spectrometry, infrared, and X-ray diffraction.

Complexos do tipo trans-[Ru(L)(NH, and L' = CNpy, 1,4-dithiane (1,4-dt), 4-mercaptopyridine (pyS) and thionicotinamide (tna), were synthesized and characterized. SAMs on gold of the complexes containing sulfur were studied by reductive desorption and SERS spectroscopy. Depending on the nature of L', the withdrawing capability of the CNpy ligand is strong enough to partially oxidize the ruthenium atom and, as a consequence, delocalize the s electronic density from the trans located ligand. The reductive desorption results showed that the stability of the SAMs is directly related to this effect.