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Characterization of Self-Assembled Monolayers of Oligo(phenyleneethynylene) Derivatives on Gold

<p>Oligo(phenyleneethynylene) (OPE) molecules are a class of fully conjugated aromatic molecules, that attract attention for their application as “molecular wires” in molecular electronic devices. In this thesis work, self-assembled monolayers (SAMs) formed from a variety of OPE derivatives have been studied. The chemical properties, structure, and packing density of the SAMs have been characterized utilizing techniques such as high-resolution X-ray photoemission spectroscopy (HRXPS), near-edge X-ray absorption fine structure spectroscopy (NEXAFS), Infrared reflection absorption spectroscopy (IRRAS), contact angle measurements, and atomic force microscopy (AFM).</p><p>In a first study, three OPE-derivatives, with benzene, naphthalene and anthracene, respectively, inserted into the backbone, and an acetyl-protected thiophenol binding group were found to form SAMs on Au(111) substrates with lower molecular surface densities and larger molecular inclination as the lateral π-system increases.</p><p>In a second study, porphyrin was introduced as the end group to a wire-like molecule such as OPE. The purpose was to obtain well-organized and functionalized surfaces with optical and redox properties. Three porphyrin-functionalized OPEs had different binding groups, an acetyl-protected thiophenol, a benzylic thiol, and a trimethylsilylethynylene group, and were found to form SAMs on gold surfaces with difference in structure and degree of order. The molecules with the acetyl-protected thiophenol binding group were found to form a high quality SAM compared to the other two. This SAM exhibits a well-ordered and densely packed layer.</p><p>This study gives rise to a better understanding of SAM formation of OPE derivatives, and will form a base for further investigations of charge transport properties of these molecular films, which is of interest for applications in molecular electronic devices.</p>

Identiferoai:union.ndltd.org:UPSALLA/oai:DiVA.org:kau-800
Date January 2007
CreatorsWatcharinyanon, Somsakul
PublisherKarlstad University, Faculty of Technology and Science, Institutionen för natur och miljö
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeLicentiate thesis, comprehensive summary, text
RelationKarlstad University Studies, 1403-8099 ; 2007:18

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