a,ω-dithiol oligo(phenylene vinylene)s for the preparation of high-quality π-conjugated self-assembled monolayers and nanoparticle- functionalized electrodes

Dwight S. Seferos, Rebecca Y Lai, Kevin W. Plaxco, Guillermo C. Bazan

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

While thioacetate-terminated oligo(phenylene vinylene)s (OPVs) have been synthesized and employed in applications involving the formation of metal-molecule-metal junctions, the synthesis and application of potentially more versatile a,ω-dithiol OPVs have not previously been described. Here, a thiomethyl-precursor route to the synthesis of a,ω-dithiol OPVs is reported and their ability to form well-ordered self-assembled monolayers (SAMs) without the addition of exogenous deprotection reagents is described. a,ω-Dithiol OPV monolayers exhibit thicknesses consistent with molecular length and are nearly defectfree, as assayed by electrochemical measurements. To demonstrate the ease with which SAMs containing these bifunctional OPVs can, in contrast to thioacetate functionalized OPVs, be further functionalized with materials other than gold, we have modified them in a single step with a sub-monolayer of cadmium selenide nanocrystals (NCs). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirm that these NC-modified films are both smooth and uniform over the largest areas investigated (> 10 μm2) and no evidence of NC aggregation is observed. To evaluate the electrochemical response of these metal-molecule- semiconductor assemblies we have fabricated NC-modified OPV SAMs with ferrocene-coated NCs. Variable-frequency alternating current voltammetry indicates that electron transfer in these assemblies is much more rapid than in analogous structures formed using simple alkane dithiols. It thus appears that a,ω-dithiol OPVs are well suited for the formation of high-quality conducting SAMs for the functionalization of gold and other surfaces.

Original languageEnglish (US)
Pages (from-to)2387-2392
Number of pages6
JournalAdvanced Functional Materials
Volume16
Issue number18
DOIs
StatePublished - Dec 4 2006

Fingerprint

Self assembled monolayers
thiols
Nanocrystals
nanocrystals
Nanoparticles
nanoparticles
preparation
Electrodes
electrodes
Metals
Gold
assemblies
Monolayers
metals
gold
cadmium selenides
Molecules
Alkanes
Voltammetry
synthesis

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Condensed Matter Physics
  • Electrochemistry

Cite this

a,ω-dithiol oligo(phenylene vinylene)s for the preparation of high-quality π-conjugated self-assembled monolayers and nanoparticle- functionalized electrodes. / Seferos, Dwight S.; Lai, Rebecca Y; Plaxco, Kevin W.; Bazan, Guillermo C.

In: Advanced Functional Materials, Vol. 16, No. 18, 04.12.2006, p. 2387-2392.

Research output: Contribution to journalArticle

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AB - While thioacetate-terminated oligo(phenylene vinylene)s (OPVs) have been synthesized and employed in applications involving the formation of metal-molecule-metal junctions, the synthesis and application of potentially more versatile a,ω-dithiol OPVs have not previously been described. Here, a thiomethyl-precursor route to the synthesis of a,ω-dithiol OPVs is reported and their ability to form well-ordered self-assembled monolayers (SAMs) without the addition of exogenous deprotection reagents is described. a,ω-Dithiol OPV monolayers exhibit thicknesses consistent with molecular length and are nearly defectfree, as assayed by electrochemical measurements. To demonstrate the ease with which SAMs containing these bifunctional OPVs can, in contrast to thioacetate functionalized OPVs, be further functionalized with materials other than gold, we have modified them in a single step with a sub-monolayer of cadmium selenide nanocrystals (NCs). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirm that these NC-modified films are both smooth and uniform over the largest areas investigated (> 10 μm2) and no evidence of NC aggregation is observed. To evaluate the electrochemical response of these metal-molecule- semiconductor assemblies we have fabricated NC-modified OPV SAMs with ferrocene-coated NCs. Variable-frequency alternating current voltammetry indicates that electron transfer in these assemblies is much more rapid than in analogous structures formed using simple alkane dithiols. It thus appears that a,ω-dithiol OPVs are well suited for the formation of high-quality conducting SAMs for the functionalization of gold and other surfaces.

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