Item – Theses Canada

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OCLC number
883455522
Link(s) to full text
LAC copy
LAC copy
Author
Hemraz, Usha Devi,1981-
Title
Twin G?̂̂̂̂̂̂C-based Rosette Nanotubes : structure and Chirality.
Degree
Ph. D. -- University of Alberta, 2010
Publisher
Ottawa : Library and Archives Canada = Bibliothèque et Archives Canada, [2012]
Description
4 microfiches.
Notes
Includes bibliographical references.
Abstract
<?Pub Inc> Rosette Nanotubes (RNTs) are self-assembled architectures, generated from a self-complementary guanine-cytosine (GC) base. In solution, six GC motifs assemble to form hexameric rosettes, which stack to form the RNTs. Both single or twin GC-based (two GC units connected by a spacer) RNTs have built-in ability to self-assemble, however the latter have enhanced stability resulting from twice the number of intermolecular hydrogen-bonding interactions, greater preorganization and amphiphilic character as well as a lower charge density and steric repulsion on their outer surface. In order to fully exploit these organic materials for biomedical and other materials applications, an in-depth study of the physical properties of the twin RNTs was necessary. This thesis explores several newly synthesized GC motifs, with variations in functionalization, core structure and connectivity, which in addition to displaying novel self-assembly behaviour, also show unique physical properties. The first chapter introduces relevant literature examples of self-assembled systems that exhibit supramolecular chirality. Notably, the sources of chirality and characterization techniques along with different factors leading to reversible supramolecular chirality inversions are presented. The second chapter describes how functionalization and core modification of newly synthesized twin GC compounds along with solvent and counterions, can influence the stability of RNTs, as indicated by their lengths at a given time. The third chapter examines unique thermo-reversible circular dichroism activity shown by achiral twin GC-based RNTs. Evidence showing that real and reversible symmetry breaking could occur using a mechanical vortex in intrinsically achiral RNT systems is presented. Chapter four describes hypotheses behind the non-assembly of certain single GC-based modules and how higher pH and hydrogen-bond acceptor solvents promoted the formation of nanostructures. The fifth chapter describes a novel mode of self-assembly for a new analogue, having two twin GC moieties connected by an alkyl chain Currently, this system shows comparable stability to RNTs having only one twin GC unit, but has the potential for increased stabilization if functionalized with solubilising groups. Chapter six describes the solid-phase synthesis and self-assembly characterization of two new twin GC motifs, bearing bioactive peptides for biological applications. Finally, an outlook of this thesis is presented.
ISBN
9780494813195
0494813199