Date of Award
Doctor of Philosophy (PhD)
Chemistry & Biochemistry
The controllable assembly of materials on the atomic or molecular level remains one of the grand challenges of chemistry. While top-down techniques such as lithography are capable of creating order over the long range, short range assembly on the order of up to 10 nanometers is currently beyond the scope of the most advanced lithographic capabilities. Self-assembly using bottom-up strategies have the potential to fill in this void, and there remains a fundamental need to have multiple strategies for the creation of materials at this scale. Herein we present research focusing on two areas of self-assembly: Alkene/imine ODCC and arylene-ethynylene macrocycle/DNA hybrids that can mediate assembly of gold nanoparticles.
Dynamic covalent chemistry (DCvC) is one technique available to chemists to synthesize matter in a controllable manner using bottom-up assembly. However, to date, the majority of DCvC reactions rely on one type of chemistry (homo-sequenced), resulting in structures with high symmetry. In contrast, the incorporation of two types of DCvC (hetero-sequenced) into one reaction has been relatively less explored. We first demonstrated that alkene metathesis and imine metathesis DCvC can be utilized in a one-pot fashion to synthesize discrete 2-D phenylene-based macrocycles. Next we showed that macrocycles made in this manner could form a 1-D polymer of macrocycles using alkyne metathesis DCvC and also prepare 3-D and 3-component shape-persistent architectures from simple building blocks.
Organic/DNA hybrids offer the potential for material whose self-assembly properties are imparted both by the hydrophobicity and directionality of the organic component as well as the base-pairing capabilities of the DNA. While most research has focused on either small molecule/DNA hybrids or polymer/DNA hybrids, discrete oligomeric architectures provided by DCvC such as arylene-ethynylene macrocycles, offer an intriguing intermediate hybrid that could be incorporated into gold nanoparticle lattices for plasmonic applications. We first explored the synthetic conditions of the on-bead amide coupling using a small library of simple organic substrates and achieved good yields. Next we demonstrated that arylene-ethynylene macrocycle/DNA hybrids can be prepared using the methodology we had developed for small molecules, and that the resulting macrocycle/DNA material can be used to assemble gold nanoparticles into both bulk aggregates and discrete assemblies of dimers depending on the DNA sequence; complementary sequences yielded bulk aggregates, while poly-adenines yielded dimers.
Okochi, Kenji D., "Self-Assembly Using Alkene/Imine Orthogonal Dynamic Covalent Chemistry and Arylene-Ethynylene Macrocycle/DNA Hybrids" (2016). Chemistry & Biochemistry Graduate Theses & Dissertations. 185.