Molecular clips based on propanediurea : synthesis and physical properties

Contains fulltext : 19075_moleclbao.pdf (publisher's version ) (Open Access)This thesis describes the synthesis and physical properties of a series of molecular clips derived from the concave molecule propanediurea. These molecular clips are cavity-containing receptors that can bind a variety of aromatic guests. This binding is a result of hydrogen bonding and pi-pi stacking interactions. Previous work on molecular clips has been limited to compounds derived from substituted glycoluril. Propanediurea, the compound on which the clips described in this thesis are based, is a molecule that is slightly more concave than glycoluril. A literature survey is presented on the synthesis of glycoluril derivatives and analogues, with special focus on propanediurea derivatives. Subsequently, synthetic efforts to prepare a variety of propanediurea derivatives are described, as well as the synthesis of a variety of molecular clips and half clips from the newly prepared propanediurea derivatives. The binding properties of these propanediurea-derived clips are investigated. It is shown that higher flexibility of the side walls increases the affinity for guests. A comparison is made between clips derived from propanediurea and clips derived from glycoluril. The former clips have a much higher affinity for resorcinol than the latter ones. It is shown that this difference is due to the slightly smaller distance between the carbonyl binding sites in the propanediurea-derived clips. Finally, a number of functionalizations of the propanediurea-derived clip molecules are treated, with the ultimate goal of using their exceptional binding properties in the construction of large supramolecular aggregates. Clips functionalized with porphyrin residues as well as studies on their complexation behavior are descibed. Resorcinol-functionalized polystyrene is used to form a columnar aggregate by self-assocation with clips functionalized at their convex sides with large aliphatic tails. In addition, a clip functionalized at its convex side with resorcinol residues is presented. This molecule can self-associate to form hyperbranched or dendrimer-like structures151 p

WOHING KANISTAN

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