Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Summary

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Abstract

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

Introduction

Electropolymerization is a polymerization technique that utilizes an applied potential to initiate the polymerization of monomeric precursors directly at the surface of an electrode and has been exploited to produce thin electroactive and/or photochemically active polypyridyl films on electrode and semiconductor surfaces.^1-4 Electrocatalysis,^5-10 electron transfer,^11,12 photochemistry,^13-16 electrochromism,¹⁷ and coordination chemistry¹⁸ have been investigated in electropolymerized films. This technique was first developed at the University of North Carolina in a Meyer-Murray colla....

Protocol

1. Synthesize 1

Synthesize 1 (PhTpy is 4'-phenyl-2,2':6',2''-terpyridine; 5,5’-dvbpy is 5,5'-divinyl-2,2'-bipyridine; Figure 4) according to the procedure outlined previously.¹⁸

2. Prepare 1.3 mM Monomer Solution of 1 in an Electrolyte Solution

1. Prepare a 0.1 M stock electrolyte solution of tetra-n-butylammonium hexafluorophosphate, TBAPF₆, in acetonitrile, MeCN.
   1. Place MeCN over activated 3 Å molecular sieves, or K₂CO₃, for 24 hr ....

Results

Electropolymer growth is most easily recognized when observing the progress of the prescribed CV experiment (Protocol Text STEP 3.3.2). Figure 5 exemplifies electropolymer growth on a 0.071 cm² (3 mm diameter) glassy carbon electrode with 1. The first cycle of the experiment produces a voltammogram roughly resembling that which is expected for a ruthenium solution of similar concentration (Figure 5, black trace) but upon successive cycles, through the 1^st.......

Discussion

Electropolymerization offers a large range of controllable variables that are not common to other techniques. In addition to standard reaction variables like reagent (monomer) concentration, temperature, solvent, etc., electropolymerization can be additionally controlled by electrochemical experiment parameters common to electrochemical methods. CV scan rates, switching potentials, and number of cycles affect the deposition of electropolymers. For example, as the number of cycles through the ligand reduction wav.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Tetrabutylammonium hexafluorophosphate for electrochemical analysis, ≥99.0%	Sigma-Aldrich	86879-25G
Acetonitrile (Optima LC/MS), Fisher Chemical	Fisher Scientific	A955-4
3 mm dia. Glassy Carbon Working Electrode	CH Instruments	CH104
Non-Aqueous Ag/Ag+ Reference Electrode w/ porous Teflon Tip	CH Instruments	CHI112
Platinum gauze	Alfa Aesar	AA10282FF
Electrode Polishing Kit	CH Instruments	CHI120
Cole-Parmer KAPTON TAPE 1/2 IN x 36 YD	Fisher Scientific	NC0099200
Fisherbrand Polypropylene Tubing 4-Way Connectors	Fisher Scientific	15-315-32B
500 ml Bottle, Gas Washing, Tall Form, Coarse Frit	Chemglass	CG-1114-15
3-compartment H-Cell for electrochemistry	Custom made H-cell with 3 compartments