Hydrogen Bonding Effects on the Reversible Reorganization of Organic Films Electrografted on Glassy Carbon Electrodes

Abstract

The electrochemical oxidation of tetrabutylammonium carboxylates derived from 6‐oxoheptanoic acid and 6‐heptynoic acid was performed on glassy carbon electrodes to generate covalently modified electrodes bearing alkyl‐ketone and alkynyl groups. These surfaces were used as models of hydrogen‐bond‐accepting surfaces to study the interaction of water with the grafted film; 1,4‐benzoquinone was used as the redox probe to demonstrate the existence of these interactions. The voltammetric behavior of this redox probe on the modified electrode changed during cycling. However, leaving this electrode to stand in the electrolyte solution allows the recovery of the starting voltammogram. These changes observed between cycling and stand time are cyclical and can be explained through a reversible reorganization effect of the grafted film, which is attributed to hydrogen bonding interactions between the functional groups present in the structure film and water present in the solvent. Supporting these surface effects, the switching behavior was absent on hydrophobic films formed with saturated aliphatic chains or by using ferrocene as non‐hydrogen bonding redox probe.

Covalent Modification of Carbon Surfaces by Direct and Redox Catalysed Oxidation of Carboxylates in Acetonitrile – Concepts and Mechanisms

“…The behaviour shown in Figure 3 opened the possibility to explore other carboxylates of a long aliphatic chain but bearing terminal groups with electrons in π-orbitals. In this way, the voltammetric behaviour of 6-heptenoate, 6-heptynoate, 6-oxoheptanoate and monomethyl adipate was registered, being these compounds an example of terminal alkene, alkyne, ketone, and ester groups [33,61] (Scheme 4).…”

“…Here, the main one that related to the reversible reorganization of the grafted films when they are tested in presence of 1,4benzoquinone as a redox probe. [61]…”

“…Most of the details about the properties of these modified electrodes by oxidation of these compounds were previously described. Here, the main one that related to the reversible reorganization of the grafted films when they are tested in presence of 1,4‐benzoquinone as a redox probe [61] …”

Electrografting of Carbon Surfaces with Aliphatic Chains and its Effect on the Rectification of Ferrocene as Redox Probe in Solution

“…In some cases, depending on the polar or non‐polar nature of the grafted film, the response of the redox probe on the grafted electrode changes during cycling procedures or by exploring the voltammetric behavior in different potential intervals. These changes have been related to reorganization effects of the film structure, either by effect of the electrode polarization [26] or by removal of traces of water contained inside the film structure [27] . The permeation of the redox probe and the supporting electrolyte ions inside the film channels is also considered as an evidence of its sieving properties [28,29] .…”

Electrochemical Surface Modification of Glassy Carbon by Using Mediated Oxidation of Palmitate Anion in Acetonitrile

“…Considering that the organic functional groups attached on the carbon surface could confer great stability and even some reactivity or catalytic properties, different electrochemical strategies have been developed in order to modify covalently surface carbon material. Some processes focused for this purpose are: anodic oxidation of amines, alcohols and carboxilates (12)(13)(14)(15)(16)(17)(18)(19)(20)(21).…”