Preparation and General Properties of Chemically Modified Electrodes Based on Electrosynthesized Thin Polymeric Films Derived from Eugenol

Abstract

Eugenol (4‐allyl‐2‐methoxyphenol) was polymerized oxidatively by cyclic voltammetry at platinum and glassy carbon electrodes. It was found that at platinum the polymerization gives rise to a uniform, compact film which could serve as a permselective membrane for analytes of small molecular size. Applications of such films in selective detection of hydrogen peroxide and nitric monoxide were proposed. Monomer oxidation at glassy carbon resulted in less compact films. Interestingly, at higher potentials a porous structure containing large amount of unoxidized o‐methoxyphenyl groups was created. This structure underwent electrochemical demethoxylation leading to the generation of redox active o‐quinone functionalities when the modified electrode was cycled in acidic solution. A small amount of p‐ quinone functionalities was also generated. As could be anticipated the redox couples were capable of mediating electrochemical oxidation of ascorbic acid and NADH. Additionally polymeric eugenol‐coated GC exhibited preconcentration capabilities towards dissolved metal cations. This effect was demonstrated on the electrochemical oxidation of preconcentrated Ce(III) and reduction of Cu(II).

Bio-based Polymer from Ferulic Acid by Electropolymerization

“…In the aqueous system, the oxidation broad peak was observed at a potential of 300 to 500 mV (vs. Ag/AgCl electrode) in the first cycle. However, no peaks were observed when repeating the cycle more than two times; this phenomenon has been observed in the case of many other phenolics Kirk 1993a, 1993b;Ciszewski and Milczarek 2001;Ezerskis and Jusis 2001;Milczarek and Ciszewski 2003;Ferreira et al 2006). During electrooxidation, many phenolic compounds in an aqueous medium undergo rapid film passivation on the electrode surface, leading to a drastic decrease in the current, whereas in an organic solvent medium, the oxidation peaks are observed at ~800 mV after repeating the cycle more than twice.…”

“…During electrooxidation, many phenolic compounds in an aqueous medium undergo rapid film passivation on the electrode surface, leading to a drastic decrease in the current, whereas in an organic solvent medium, the oxidation peaks are observed at ~800 mV after repeating the cycle more than twice. This implied that electrons tunneled through the oxidized polymer film formed on the electrode surface, or that the film was degraded (a) (b) or ruptured from the electrode, which allowed ferulic acid to reach the electrode surface Kirk 1993a, 1993b;Ciszewski and Milczarek 2001). Electropolymerization Figure 2 shows the change in the electrode potential versus time at constant-current (0.025 mA/cm 2 ) electrolysis with the apparatus.…”

Electrochemical Oxidation of Fragrances 4-Allyl and 4-Propenylbenzenes on Platinum and Carbon Paste Electrodes

“…16 4-allylbenzenes (4-allylanisole and eugenol) and 4-propenylbenzenes (trans-anethole) are studied to undergo electrochemical polymerization giving rise to either conducting or insulating films. [17][18][19] The anodic methoxylation of alkenylbenzenes includes anethole and isosafrole on graphite and platinum, which can be converted to free aldehyde, a valuable fragrance compound and an intermediate for organic synthesis. [20][21][22][23] The present work is concerned with the measurement of aromatic substituent effects and structural elucidation of 4-allyl and 4-propenylbenzenes.…”

Permselective Properties of Electropolymerized Guaiacol Derivatives

“…Discussion of the polymerization mechanism is out of the scope of this paper and may involve steps previously suggested for compound 2 [14,15]. Since the oxidation of omethoxyphenols can proceed through 1-or 2-electron paths [15] it is rather difficult to calculate the thickness of the polymeric films which are formed from different monomers used.…”

“…Since the oxidation of omethoxyphenols can proceed through 1-or 2-electron paths [15] it is rather difficult to calculate the thickness of the polymeric films which are formed from different monomers used. However, on the basis of the previous assumptions made for poly-2 [14] we can estimate that the polymerization charge of 1 mC cm À2 gives 75 to 150 monolayers of phenols molecules polymerized on the electrode surface.…”