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dc.contributor.advisorBarybin, Mikhail V.
dc.contributor.advisorBerrie, Cindy L.
dc.contributor.authorOkeowo, Monisola Khadijat
dc.date.accessioned2020-01-17T23:01:13Z
dc.date.available2020-01-17T23:01:13Z
dc.date.issued2019-05-31
dc.date.submitted2019
dc.identifier.otherhttp://dissertations.umi.com/ku:16332
dc.identifier.urihttp://hdl.handle.net/1808/29895
dc.description.abstractThe use of molecular electronics to build nano-scale devices is potentially applicable to the development of electronic components, such as wires, switches, or diodes. The work described herein involves the self-assembly of azulene-based materials on atomically flat gold substrates with emphasis placed on the formation, stability, orientation, topography, thickness, and molecular packing of isocyano and thiolate junctions as well as the underlying gold films. The techniques employed in this study include Reflection-Absorption Infrared (RAIR) spectroscopy, optical ellipsometry, and Atomic Force Microscopy (AFM). In chapter I, a review of self-assembly and the coordination of organic molecules to gold substrates are discussed. An emphasis is placed on the use of the azulenic linker for electron transport, which may be a useful building block for molecular wires. The isocyano-azulenic and biazulenic self-assembled monolayers (SAMs) on Au (111) studied in the Barybin group are discussed with emphasis placed on the junction groups’ nature and their influence on the physicochemical properties of the azulenic SAMs. The methods of characterization and sample preparation of gold substrates for SAM formation are discussed in chapter II. New azulenic SAMs featuring nitrile-substituted isocyanoazulene adsorbed on Au (111) are described in this chapter. Ellipsometry and RAIR techniques were utilized in the characterization of these new nitrile-substituted isocyanoazulenic SAMs. The positions of the nitrile and isocyanide groups on the azulene framework were varied to control the binding orientation of the azulene molecules adsorbed on Au (111). Nitrile groups incorporated into the azulenic scaffold acted as remote spectroscopic reporters, while the isocyanide groups were used in anchoring the molecules to the gold surface. The results revealed that remote nitrile vibrational reporters are sensitive to electronic perturbations exerted by the coordination of isocyanoazulenic motif to the gold surface. The first examples of employing both isocyanide and thiolate junction groups within the same molecule are described in chapters III and IV. In Chapter III, isocyanoazulenylthiolate derivatives’ SAMs are addressed. The study involves first p-linker featuring both -NC and -SH termini in the same molecule self-assembled on gold by employing the 2,6-azulenic framework. A direct comparison of the new asymmetric system to the analogous symmetric di-isocyano azulenic system adsorbed on gold was performed. Chapter IV describes an extension of the azulenic framework studied in the previous chapter. In Chapter IV, a biazulene linker, featuring both -NC and -SH termini within the same molecule, was adsorbed on Au (111), utilizing the bi-6,6′-azulenic core, for the purpose of electron transport from one electrode to the other. Characterization of the azulenic and biazulenic monolayer films in chapter III and IV was performed using ellipsometry and RAIR spectroscopy. The isocyano and thiolate junction groups were used in the SAM formation. The study of the competitive adsorption that emphasizes the stronger binding affinity of the thiolate junction group to gold is also addressed. The carbonyl groups of the zero-valent chromium pentacarbonyl-Cr(CO)5 motif anchored to the azulenic scaffold were employed as remote spectroscopic reporters in probing the 6-mercaptoazulenic and 2-mercaptobiazulenic motif on the Au(111) surface in both chapters. Overall, the various spectroscopic and physical methods showed similar result: isocyano and thiol containing azulenes were bound to Au (111) surfaces in an upright orientation. In chapter V, AFM techniques are used to investigate the molecular packing, and geometry, of the underlying gold and the functionalized azulene molecular layer on the film. The first AFM topography images of isocyano- and mercaptozulene SAMs are studied. Contact mode AFM was utilized in ambient conditions to investigate the atomically and molecularly resolved images. Optimal packing of the molecular films of 2-mercaptoazulene SAM was achieved using a displacement route of 2-isocyanoazulene preform in the self-assembly, and the AFM images of 2-mercaptoazulene SAMs indicate well-ordered molecules formed on the film. The 2-isocyanoazulene SAMs AFM image was not as clear as the 2-mercaptoazulene analogue. The upright-oriented 2-mercaptoazulene molecules are arranged face-to-face, tilted in a similar direction, and aligned in a π-stacking repeated pattern.
dc.format.extent185 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectChemistry
dc.subjectAzulene SAMs
dc.subjectgold substrates
dc.subjectMaterial science
dc.subjectMolecular conductivity
dc.subjectmolecularly resolved images
dc.subjectSelf-assembled monolayers
dc.titleMaterials for Molecular Electronics Devices: Anchoring Azulene Derivatives to A Gold Surface via Molecular Self-Assembly
dc.typeDissertation
dc.contributor.cmtememberJackson, Timothy A.
dc.contributor.cmtememberElles, Christopher
dc.contributor.cmtememberCamarda, Kyle V.
dc.thesis.degreeDisciplineChemistry
dc.thesis.degreeLevelPh.D.
dc.identifier.orcid
dc.rights.accessrightsopenAccess


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