Covalent modification of carbon surfaces with ferrocene groups through a self-mediated oxidation of tetrabutylammonium salts of ferrocene-carboxylic acids

Use of a Wedge Scheme to Describe Intermolecular Proton-Coupled Electron Transfer through the H-bond Complex Formed Between a Phenylenediamine-Based Urea and 1,8-Naphthyridine

“…This was done by using a procedure reported by Gonzalez and co-workers for methylating the surface of GC through the ferrocene-mediated oxidation of acetate in acetonitrile. 45 CVs of U(H)H taken with these purposely "fouled" GC electrodes do indeed show two peaks on the return scan as seen with Pt electrodes. (See Figures S4 and S5 in the Supporting Information.)…”

Role of the Supporting Electrolyte Ions and Additives on the Electron Transport Properties of Electrografted Films Bearing Ferrocenyl Moieties

“…The surface of these graphitic carbon materials is rich in π‐electron density and therefore is prone to exert surface reactions with free radicals to yield covalently‐linked films [34–36] . Examples of direct reactions to covalently modify carbon surfaces with films bearing ferrocene molecules are the electrochemical oxidation of ferrocenylalkylcarboxylates, [37,38] ferrocenylalkynyl lithium compounds, [39–41] and ferrocenylalkylamines, [42,43] whereas in cathodic processes, the modification was reached by reduction of haloalkylferrocenes [44] . In agreement with this radical grafting concept, chemical modification of carbon surfaces has also been obtained from the spontaneous decomposition of ferrocenylalkynyl compounds [45] …”

“…For example, for nitrophenyl groups electrografted on carbon electrodes, the voltametric reduction pattern can be easily influenced by ion‐pairing, hydrogen bonding and/or proton transfer processes with traces of water contained in the solvent (most commonly, acetonitrile) [50] . Contrary, when the grafted film bears ferrocene molecules, their oxidation is less prone to exert this kind of interactions, which give rise to a voltammetric behavior with more ideal features [16,37–44] . Nevertheless this improvement, the real amount of ferrocenyl groups into the grafted films seems to be still higher than that obtained by integration of the oxidation waves.…”

Effect of Electrolyte Ions on the Formation, Electroactivity, and Rectification Properties of Films Obtained by Electrografting

“…These kind of pre‐waves at the foot of the main wave are not exclusive of the reduction of surface nitrobenzene groups because they were also observed during the reduction of other surface redox groups . In the case of the anodic oxidation of grafted groups like ferrocene, this sort of pre‐waves have not been observed …”

“…[11] In the case of the anodic oxidation of grafted groups like ferrocene, this sort of pre-waves have not been observed. [30][31][32] Therefore, the non-ideal behavior of the voltammograms obtained by reduction of the grafted film is related to the generation of nitrobenzene radical anion species, whose stability inside the grafted film can be influenced, in a first approach, by ion-pairing, hydrogen bonding and/or proton transfer processes. The probable intervention of these processes during the reduction of the grafted nitrobenzene moieties represents a high level of complexity and consequently, the intervention of any hydrogen bonding or proton transfer processes promoted by the presence of traces of water in the solvent was minimized using anhydrous acetonitrile and supporting electrolytes purified by recrystallization and dried overnight in an oven at 70°C.…”