Doctor of Philosophy (PhD)
Nanomaterials derived from a group of uniform materials based on organic salts (GUMBOS) have been introduced into the scientific literature through many analytical, biological, and technological applications. These nanomaterials, referred to as nanoGUMBOS, have been shown to display a number of interesting properties including fluorescence, magnetism, tumor targeting, and optoelectronic properties. Herein, we present major studies on nanoGUMBOS including synthesis and size-control, chiral molecular imprinting in polymers, as well as investigation of optical properties and quantum yield of fluorescent semiconductor-based nanoGUMBOS. Various strategies were introduced for production of well-defined nanoGUMBOS. Specifically, several methods based on sonochemistry, microwave, cyclodextrin, and surfactant-assisted syntheses of nanoGUMBOS are described while evaluating the efficiency of each technique in controlling size, morphology, and uniformity of nanoparticles. The systematic variations in experimental parameters such as concentration, cation-to-anion ratio, as well as presence and type of templates introduced for the formation of nanoGUMBOS were also investigated. Moreover, imidazolium-based ionic liquid crosslinkers were tested as platforms for chiral imprinting under aqueous conditions. Using photoinitiated dispersion polymerization, molecularly imprinted polymeric nanoGUMBOS were designed with recognition properties for L-tryptophan. Rebinding studies were performed in batch mode analysis using fluorescence spectroscopy. Strong interactions between GUMBOS and L-tryptophan made imprinting possible in aqueous media. Various spacers between the imidazolium rings of the cation afforded the presence of secondary interactions responsible for distinctive enantiorecognition behavior of these polymeric nanoparticles. In this regard, these vinylimidazolium ionic liquids were polymerized using gamma irradiation, for potential application in drug loading. Furthermore, carbazole-based nanoGUMBOS were investigated as fluorescent materials for potential applications in blue organic light emitting devices. These nanoGUMBOS were synthesized using a reprecipitation method in the absence or presence of 2-hydroxypropyl-â-cyclodextrin, in order to tune the size and optical properties of the nanoparticles. The carbazoleimidazole-based cation was coupled with different couteranions: iodide ([I]), trifluoromethanesulfonate ([OTf]), and bis(pentafluoroethylsulfonyl)imide ([BETI]). Absolute quantum yields were compared for each type of nanoGUMBOS synthesized under different experimental conditions. Doping with the transition metal Cu2+ was also explored as an alternative strategy for tuning the quantum yield of nanoGUMBOS, which was enhanced by optimizing the molar percentage of dopant to host.
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Hamdan, Suzana, "Nanoscale GUMBOS: Size-Control, Characterization, and Applications as Enantioselective Molecularly Imprinted Polymers and Fluorescent Materials" (2015). LSU Doctoral Dissertations. 1580.
Warner, Isiah M.