CUCURBIT[N]URIL FUNCTIONALIZATION AND INCORPORATION INTO METAL-ORGANIC ASSEMBLIES

Abstract

Molecular containers have been widely studied due to their unique ability to recognize guest molecules. Host compounds have been used in various applications including sensing, separations, and the development of smart materials due to these binding properties. The curcurbit[n]uril (CB[n]) family of macrocyclic containers are known for their high binding affinities and selectivities towards guest molecules in water. Altercation to the size and shape of the CB[n] cavity or addition of functional groups might expand potential applications.Chapter 1 introduces supramolecular chemistry, specifically that of molecular containers. A review of CB[n] chemistry describes their exceptional binding properties and potential usage. However, poor water solubility limits the biological applications of CB[n]. The development of acyclic CB[n] and incorporation of cyclic CB[n] into metal-organic polyhedra (MOP) are described to enhance the potential biomedical properties of these containers. Chapter 2 describes the extension of the glycoluril backbone of the acyclic CB[n]. The synthesis of the conformationally mobile S-shaped glycoluril pentamer building block and two new acyclic CB[n] receptors P1 and P2 are reported. In the presence of guests, P2 adapts its conformation to form 1:1 P2·guest complexes. The binding free energy pays the energetic price for conformer selection. This energetically unfavorable conformer selection results in significantly decreased Ka values of P1 and P2 compared to Tet1 and Tet2. Chapter 3 presents the self-assembly of rigid-rod dipyridine ligand III-1 with M(en)(NO3)2 (M = Pd, Pt) to afford triangular (III-3, III-5) and square (III-4, III-6) supramolecular coordination complexes. The binding affinity of III-1 towards CB[n]-type containers result in the formation of triangular [4]molecular necklaces ([4]MNs, III-7 – III-10) either by one-pot or post complexation approaches as evidence by 1H NMR, DOSY NMR, and ESI-MS. Chapter 4 investigates the self-assembly of three iron-based metal-organic polyhedra systems (IV-6, IV-12, and IV-17). CB[7] can be mechanically interlocked onto the edges of the scaffolds during the self-assembly process to yield MOPs IV-7, IV-13, and IV-18 as evident by 1H and DOSY NMR. Full saturation of the edges could not be achieved due to the slippage of the CB[n] units during the self-assembly process.