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UBC Theses and Dissertations

DNA-inspired Janus AT and GC heterocycles : synthesis, structural analysis and self-organization Asadi, Ali


Inspired by the significance of hydrogen bond driven self-organization, especially from the base-pairing interactions of double helical DNA, this dissertation discusses the synthesis and characterization of a number of DNA-inspired self-complementary heterocycles and the supramolecular ensembles derived from them. Specifically, two projects have been completed. Each of these projects addresses the high yielding syntheses of heterocycles with defined hydrogen bond accepting and donating capabilities designed to self-assemble under the general purview of base pairing. The first chapter provides an introduction to general concepts such as base-pairing as well as an outline of the diverse synthetic supramolecular ensembles that have been prepared by utilizing such interactions. Chapter 2 focuses on the syntheses and solid-state structures of three self-complementary DNA-inspired heterocycles which contain ADA-DAD hydrogen bond acceptor-donor patterns (Janus AT 1-3). These novel heterocycles represent diaminopurine thymine hybrids that, in two of the three cases, relate to previously reported heterocyclic hybrids of guanine and cytosine. All three heterocycles crystallized and afforded the first X-ray crystal structures of such heterocycles and revealed their extended H-bonded arrays. This chapter also introduces the synthetic development to build Janus AT deoxynucleosides, capable of being oligomerized, as the current trend of this project. The potential use of Janus AT heterocycles in DNA and RNA recognition is briefly discussed as well. Chapter 3 will disclose the synthesis and characterization of a DNA-inspired self-complementary heterocycle capable of AAD-DAA hydrogen bond pairing, which self-organizes to a tetrameric rosette, that unlike a G-quartet,needs no metal binding or peripheral component for pre-organization (Janus GC 1). Notably, ESI-MS, variable temperature ¹H-NMR, 2D-NOESY and DOSY ¹H-NMR have been exploited to validate the tetrameric stoichiometry in this non-covalent rosette comprising twelve H-bonds. At the end of each of these chapters, a section pertaining to ongoing efforts and proposed future research is included.

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