Designing Stable Redox-Active Surfaces: Chemical Attachment of an Osmium Complex to Glassy Carbon Electrodes Prefunctionalized by Electrochemical Reduction of an In Situ-Generated Aryldiazonium Cation

Abstract

The production of stable redox-active layers on electrode surfaces can lead to improvements in electronic device design. Enhanced stability can be achieved by pretreatment of electrode surfaces to provide surface chemical functional groups for covalent tethering of redox complexes. Herein, we describe pretreatment of glassy carbon electrodes to provide surface carboxylic acid groups by electro-reduction of an in situ-generated aryl diazonium salt from 3-(4-aminophenyl)propionic acid. This surface layer is characterized by attenuated total reflection infrared spectroscopy, atomic force microscopy, and electrochemical blocking studies. The surface carboxylic acid generated is then used to tether an osmium complex, [Os(2,2'-bipyridyl)2(4-aminomethylpyridine)Cl]PF6, to provide a covalently bound redox-active monolayer, E(0) ' of 0.29 V (vs Ag/AgCl in phosphate buffer, pH 7.4), on the pretreated glassy carbon electrode. The layer proves stable to pH, temperature, and storage conditions, retaining electroactivity for at least 6 months.

Evaluation of performance and stability of biocatalytic redox films constructed with different copper oxygenases and osmium-based redox polymers

“…Introduction of amine functional groups to graphite electrodes was achieved via the in-situ generation and subsequent electro-reduction of the diazonium cation obtained from 1,4-phenylenediamine [59][60][61]. Briefly, 8 mM of NaNO 2 was added to a 10 mM acidic solution (0.5 M HCl) of 1,4-phenylenediamine to generate the diazonium moiety.…”

Carbon surface derivatization by electrochemical reduction of a diazonium salt in situ produced from the nitro precursor

“…The major advantage of this approach is that the direct introduction of numerous surface-bound functional groups [6,15,16] or biological materials [17,18] is achieved whilst avoiding harsh oxidative conditions. Recently, a simpler procedure enables surface derivatization through the reduction of diazonium salts in situ produced by a standard diazotization reaction of the corresponding amines [19][20][21][22][23][24][25].…”

Covalent Modification of Glassy Carbon Surfaces by Using Electrochemical and Solid‐Phase Synthetic Methodologies: Application to Bi‐ and Trifunctionalisation with Different Redox Centres

“…[27,[35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50] The main strategy consists of immobilising a 4-nitrophenyl group at the carbon surface by reducing the corresponding diazonium salt, reducing the nitro group to an amine group, then allowing subsequent chemical modifications. [27,35,36,41,43,48,50] Other examples include the immobilisation of a 4-carboxyphenyl group, [39,42,46,47] 4-(chloromethyl)phenyl group, [37,38] 4-(aminoethyl)phenyl group, [40] and more recently phenylmaleimide group, [44] phenylazide or phenylacetylene groups, [45] and boronic acid group, [49] followed by further chemical modification at the reactive groups for the preparation of single modified carbon A C H T U N G T R E N N U N G electrodes.…”