Cyclic (ring) and multicyclic polymer chain architectures are topologically intriguing and have inspired expanding research interests. A class of multicyclic polymer topologies, including three subclasses of spiro-, bridged- and fused-forms, are particularly unique not only from the topological geometry viewpoint but also from their programmed folding structures of biopolymer relevance. We have so far demonstrated an electrostatic self-assembly and covalent fixation (ESA-CF) protocol as a powerful synthetic approach, where ion-paired linear or non-linear polymer self-assemblies are employed as key intermediates. As a showcase example, we have recently achieved the ESA-CF construction of a topologically significant fused-tetracyclic K3,3 graph polymer, known as a prototypical non-planar graph in topological geometry, and remarkably identified in cyclic polypeptides (cyclotides) of diverse biofunctions, by using a uniform-size dendritic polymer precursor having six cyclic ammonium salt end groups carrying two units of a trifunctional carboxylate counteranions. The K3,3 graph polymer product was isolated by the preparative SEC fractionation technique to be separated from the ladder-form topological isomer product formed concurrently. Moreover, a variety of multicyclic polymer topologies of the three subclasses and their hybrid-forms, including a triply-fused tetracyclic and a quadruply-fused pentacyclic forms (unfolded tetrahedron-graph, and “shippo”-form, respectively) have been constructed through the ESA-CF process in conjunction with a tandem alkyne-azide addition, i.e., click, and olefin metathesis, i.e., clip, reactions.

Topological polymer chemistry designing macromolecular graph constructions

255th National Meeting (2018)

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