showing 3 related works from this author
Modelling electrocatalysis of hydroquinone oxidation by nicotinamide adenine dinucleaotide coenzyme encapsulated within SBA-15 and MCM-41 mesoporous …
2006
The electrochemical response of NADH associated to two mesoporous aluminosilicates, MCM-41 and SBA-15, is described upon attachment of such materials into polymer-film electrodes. The studied materials display a significant electrocatalytic activity towards the oxidation of 1,4-dihydrobenzoquinone, H2Q. Two models for describing the electrocatalytic process, based on the general theory of mediated electrocatalysis and the Lovric and Scholz formulation of the voltammetry of microparticles are discussed. Voltammetric and chronoamperometric data indicate that the electrocatalytic process involves the formation of a surface-confined NADH–H2Q adduct in the case of SBA-15, while a surface reactio…
Anionic Organic Guests Incorporated in Zeolites: Adsorption and Reactivity of a Meisenheimer Complex in Faujasites
2005
Zeolites are suitable microporous hosts for positively charged organic species, but it is believed that they cannot adsorb organic anions. Pure Meisenheimer complex, derived from reduction of 2,4-dinitroaniline with NaBH4, was adsorbed inside faujasite cavities. Evidence for the internal incorporation of this negatively charged reaction intermediate comes from 1) XPS elemental analysis as a function of the depth of penetration into the particle, 2) the remarkable blue shift in lambda(max) of the Meisenheimer complex adsorbed on zeolite (ca. 470 nm) as compared to that in acetonitrile (580 nm) and 3) from the lack of reactivity with size-excluded hydride-acceptor reagents. Evidence is provid…
Electrochemical Monitoring of Compartmentalization Effects in the Stability of Meisenheimer Anions Supported in Hydrotalcite and X and Y Zeolites
2005
Meisenheimer anions (MS - ) derived from 2,4-dinitroaniline are stabilized into Li + - and Na + -exchanged zeolites X and Y forming alkali ion-MS ion pairs. Upon attachment of the zeolites to polymer film electrodes immersedinto Et 4 N + /MeCN and Li + /MeCN electrolytes, boundary-associated MS - ions display two oxidation processes at +0.40 and +0.65 V vs. AgCl/Ag. This response sharply contrasts with that recorded for MS - in solution and incorporated within hydrotalcite, for which a unique oxidation peak at +0.35 V is recorded. The electrochemistry of zeolite-associated MS - can be described in terms of an unusual electron-transfer/ chemical reaction/electron-transfer/comproportionation …