Mixed Azide-Terminated Monolayers:  A Platform for Modifying Electrode Surfaces

Mixed Azide-Terminated Monolayers:  A Platform for Modifying Electrode Surfaces

We have prepared and characterized mixed self-assembled monolayers (SAM) on gold electrodes from azido alkane thiols and various ω-functionalized alkane thiols. In the presence of copper(I) catalysts, these azide-modified surfaces are shown to react rapidly and quantitatively with terminal acetylene...

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Bibliographic Details
Published in:Langmuir Vol. 22; no. 6; pp. 2457 - 2464
Main Authors: Collman, James P, Devaraj, Neal K, Eberspacher, Todd P. A, Chidsey, Christopher E. D
Format: Journal Article
Language:English
Published: Washington, DC American Chemical Society 14-03-2006
Subjects:
Azides - chemistry
Catalysis
Chemistry
Electrochemistry - instrumentation
Electrodes
Exact sciences and technology
General and physical chemistry
Spectrum Analysis - methods
Surface Properties
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
Photoelectron
Self assembly
Monolayer
Gold
Surface reaction
Thiol
Hydrocarbon
Reaction order
Transition metal
Modified catalyst
X ray
Metallocene
Acetylene
Electrodes
Azides
Mixed monolayer
Chemistry
Alkane
Electrochemistry
Reaction time
Copper I
Rate constant
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Summary:We have prepared and characterized mixed self-assembled monolayers (SAM) on gold electrodes from azido alkane thiols and various ω-functionalized alkane thiols. In the presence of copper(I) catalysts, these azide-modified surfaces are shown to react rapidly and quantitatively with terminal acetylenes forming 1,2,3-triazoles, via “click” chemistry. The initial azide substituents can be identified and monitored using both grazing-angle infrared (IR) and X-ray photoelectron spectrosopies. Acetylenes possessing redox-active ferrocene substituents react with the azide-terminated mixed SAMs and electrochemical measurements of the ferrocene-modified SAM electrodes have been used to quantify the redox centers attached to these platforms. Time-resolved electrochemical measurements have enabled us to follow the formation of these ferrocene centers and thus to measure the rate of the surface “click” reaction. Under optimal conditions this well-behaved second-order reaction takes place with a rate constant of 1 × 103 M-1 s-1. Typical reaction times of several minutes were realized using micromolar concentrations of acetylene. These techniques have been used to construct well-characterized, covalently modified monolayers that can be employed as functional electrode surfaces.
Bibliography:istex:66FD2A21915620E249EB8FAF32E8CB1E7FE55AFD
ark:/67375/TPS-28S6LKC8-0
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To whom correspondence should be addressed: Email jpc@stanford.edu, chidsey@stanford.edu. Fax: (+1)650-725-0259
ISSN:0743-7463
1520-5827
DOI:10.1021/la052947q