Cyclo(18)carbon
Cyclo(18)carbon, also known as C18, is an allotrope of carbon consisting of a ring of 18 carbon atoms. This molecule has been a subject of significant interest in chemistry and materials science due to its unique structure and potential properties. Theoretical studies predicted it to be a highly strained molecule with alternating single and triple bonds (polyynic structure) or with alternating single and double bonds (cumulenic structure).
The successful synthesis and characterization of cyclo(18)carbon were reported in 2019. The synthesis involved the on-surface dehalogenation of a precursor molecule on a copper surface within an ultra-high vacuum environment, observed via atomic force microscopy (AFM). The experimental results showed a structure consistent with a polyynic configuration, exhibiting alternating single and triple bonds.
Cyclo(18)carbon is of interest for several reasons. Its small size and defined structure make it a potential building block for more complex carbon-based nanomaterials. Furthermore, its unique electronic properties, stemming from its cyclic structure and bond alternation, suggest potential applications in molecular electronics. Its high reactivity, resulting from the ring strain, also makes it a promising candidate for chemical reactions and functionalization, potentially leading to the creation of novel carbon-based compounds with tailored properties. However, due to its recent synthesis, many aspects of its behavior, stability, and potential applications are still under active investigation.