Discrete and Polymeric Complexes Comprising Bis-nor-seco-CB and Oligoammonium Ions
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ABSTRACT Title of Document: DISCRETE AND POLYMERIC COMPLEXES COMPRISING BIS-NOR-SECO-CB AND OLIGOAMMONIUM IONS Regan C. Nally, Ph.D., 2009 Directed By: Professor Lyle D. Isaacs Department of Chemistry and Biochemistry Supramolecular architectures composed of multiple components are challenging to produce, as the enthalpic gain must be greater than the entropic penalty of strict geometrical arrangements. Therefore, it is the goal of supramolecular chemists to strategically design and synthesize molecules that will exhibit selectivity toward formation of a particular complex. This dissertation describes the formation of supramolecular architectures of increasing size and is organized in the following way. Chapter 1 introduces the reader to the field of supramolecular polymer chemistry. Chapter 2 describes the synthesis of a series of monovalent ditopic guests (II-1 - II-6) and their complexation properties toward double cavity cucurbituril host bis-ns-CB. We observed the preferential formation of 1:1, 2:2, and oligomeric complexes rather than the desired n:n supramolecular polymers. Guest II-7 which contains a longer biphenyl spacer successfully precludes the formation of the 1:1 complex but results in the formation of the 2:2 complex (bis-ns-CB2*II-72) rather than supramolecular polymer. Guest II-8 is heterovalent and ditopic and is shown to reversibly form 2:2 and 1:2 complexes (bis-ns-CB2*II-82 and bis-ns-CB*II-82) in response to changes in host:guest stoichiometry. Lastly, this equilibrium can be manipulated by the addition of exogenous CB which selectively targets the hexanediammonium ion binding region of II-8 and delivers the penta-molecular complex bis-ns-CB*II-82*CB2. Chapter 3 describes the formation of a main chain supramolecular polymer from a mixture of poly(diallyldimethylammonium chloride) (III-1) and bis-ns-CB. The bis-ns-CB molecular container behaves as a molecular handcuff, bringing together two ends of individual polymers to form III-1n* bis-ns-CBm, resulting in an extension of the length of polymer. The effect of bis-ns-CB on the physical properties of the polymer was investigated using viscometry in aqueous solution. A decrease in the ηrel was observed upon increasing concentrations of bis-ns-CB to a solution of III-1. Atomic force microscopy (AFM), and diffusion-ordered spectroscopy (DOSY) were performed to probe the mode of interaction between polymer III-1 and bis-ns-CB. Collectively, the data supports the two roles for bis-ns-CB: 1) as a deaggregation agent, and 2) as a molecular handcuff that non-covalently links individual polymer strands resulting in overall extension of the polymer.