Synthesis of topological isomers from manisyl-substituted polypyridine ligands

Molecular representations of chemical topologies such as concatenated rings, knots, and links are an aesthetically attractive yet synthetically challenging group of structures that comprise the basis of this doctoral thesis work. In order to tackle such structures using a metal template approach a common Pd catalyzed cross-coupling protocol was developed for the synthesis of aryl-substituted polypyridine ligands, mainly 2,2 ′-bipyridine, 1,10-phenanthroine, and 2,2′:6 ′,2″-terpyridine, from common intermediates. The aryl-substitutnt manisyl was chosen for its ability to improve solubility in this class of compounds while simultaneously providing functionality for structural elaboration (manisyl = 4-methoxy-2,6-dimethylphenyl). The chelating ability of the polypyridine ligands enables coordination with transition metal ions and facilitates formation of rigid templates with latent topology.; Achiral and chiral [2]catenanes were prepared from manisyl-substituted terpyridine, and its asymmetric sibling pyridyl-phenanthroline, respectively. In some cases an undesired figure eight complex was the major product and could be controlled by optimizing the cyclizing components. This section highlights the formation of template free catenanes and debuts the use of pyridyl-phenanthroline toward a topological target.; Replacing anisyl (4-methoxyphenyl) for manisyl enabled structural elaboration on a previously prepared triskelion template, which is a precursor to a D₃ symmetric trefoil knot . Attempts to complete a trefoil knot using metal mediated oxidative coupling of aryl-halides and stannanes are discussed.; A precursory two-ring intermediate en route to an orthogonal presentation of a Borromean link was prepared by a multi-step sequence of macrocyclization, threading and complexation procedures. Attempts to incorporate and cyclize a third ring component are described. The crystal structure of the advanced intermediate confirms an orthogonal arrangement of the two rings and the conformation of the binding site for the third ring component. An alternative third ring component for a new two-ring intermediate is proposed.; Fluorescence investigations of the manisyl-substituted ligands unveil specific members with moderate to high quantum yields (Φ_f) (Φ_f = 0.50–0.87). Comparison studies show 5-manisyl-2,2′-bipyridine to be the minimum structural chromophore. The addition of zinc(II) and proton cause pronounced red shifts and quenching in the fluorescence emission, suggesting a charge transfer mechanism.