Synthesis of new allotropes of carbon: Cyclocarbon catenanes

The last 35-years have seen many advances in the field of new carbon allotropes, from fullerene chemistry to carbon nanotubes and graphene.

Inspired by the huge impact of these new forms of carbon, we aim to create new carbon allotropes through the synthesis of cyclic molecules, cyclocarbons composed of only sp-hybridized carbon atoms, which are stabilized by the encapsulation of several macrocycles to form catenanes.

The proposed project combines recent advances in polyyne chemistry (the field of the applicant's PhD) with supramolecular chemistry to create and study novel compounds: cyclocarbon catenanes.

This project will include extensive synthetic work to find the most efficient working scheme for the formation of a stable cyclo[40]carbon catenane with suitable macrocycles. Dicobalt complexes will be incorporated into the polyyne precursors to form masked alkyne equivalents (MAEs).

Active metal template (AMT) cross-coupling and/or homo-coupling reactions will be applied with MAEs to synthesize polyyne rotaxanes with suitable macrocycles on the polyyne thread.

Cyclo-oligomerization using another AMT coupling, under high dilutions, is expected to yield a cyclo-tetramer, which can be unmasked to afford the target C40 catenane.

The electronic nature of the target compounds will be studied using a range of techniques, including nuclear magnetic resonance spectroscopy, UV-vis absorption and fluorescence spectroscopy, electrochemistry, as well as time-resolved IR and Raman studies, additionally characterized with X-ray crystallography in the solid-state.

These efforts will focus on exploring structure, reactivity, and physical properties of cyclocarbon molecules, to determine experimentally whether they are acetylenic or cumulenic in their ground states and excited states.