Synthesis and properties of bis-corannulenes

Corannulenecarbaldehyde and corannulenylmethyl triphenylphosphonium bromide are combined through the Wittig olefination reaction to furnish dicorannulenylethene with 70% yield. A subsequent oxidative photocyclization leads to annulation of the corannulene nuclei to produce a C42H18 nanographene structure in 59% yield. Interestingly, only the trans isomer of the dicorannulenylethene forms cocrystals with fullerene C60 through concave-convex and convex-convex π-π stacking interactions. The Mallory photocyclization could be extended to a phenanthrene-based diarylethene precursor to yield a large bicorannulene system.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversityFinancial support from the Ministry of Education Singapore under the AcRF Tier 1 (2019-T1-002-066) (RG106/19) (2018-T1-001-176) (RG18/18); Agency for Science, Technology and Research (A* STAR)-AME IRG A1883c0006; and NTU (04INS000171C230) is gratefully acknowledged