Interlocked molecules with unusual properties: luminescent rotaxanes and mechanically chiral catenanes

Abstract

Once merely a synthetic curiosity, mechanically interlocked molecules (MIMs) have become readily accessible structures thanks to the development of template approaches, and their properties are now being explored for applications in materials, catalysis, sensing, and molecular machines. This thesis describes work to expand the understanding and applications of MIMs prepared via an active template approach. In the first chapter, topics related to MIMs are discussed with the aim of introducing the work presented in chapters 2-4. These include the active template copper-mediated azide alkyne cycloaddition, emissive rotaxanes, and the stereogenic units that can arise from the mechanical bond. In the second, the synthesis of a selection of rotaxanes based on a thermally activated delayed fluorescence (TADF) emitter scaffold is reported. The effect of the mechanical bond on the TADF properties of three of these emitters was investigated and was shown to improve key photophysical properties. In the third, the synthesis of cycloplatinated rotaxanes is explored for potential applications in luminescent materials. A robust procedure could not be developed. However, the platination exhibited unexpected regioselectivity depending on the components used to prepare the rotaxanes, highlighting the ability of the mechanical bond to influence unexplored reactivities. Finally, in the fourth chapter, the concept of topological chirality in MIMs is discussed. Using a chiral auxiliary approach developed by the Goldup group, a chiral catenane is synthesised where an exocyclic double bond determines the orientation of one ring, challenging common terminology used to describe such stereogenic units.

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Identifiers

ORCID for Stephen Goldup: orcid.org/0000-0003-3781-0464

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