An Ortho-Tetraphenylene-Based Gelander Architecture Consisting Exclusively of 52 sp2-Hybridized C Atoms

A new type of Gelander molecule based on a ortho-tetraphenylene core is presented. The central para-quaterphenyl backbone is wrapped by a 4,4'-di((Z)-styryl)-1,1'-biphenyl banister, with its aryl rings covalently attached to all four phenyl rings of the backbone. The resulting helical chiral bicyclic architecture consists exclusively of sp(2)-hybridized carbon atoms. The target structure was assembled by expanding the central ortho-tetraphenylene subunit with the required additional phenyl rings followed by a twofold macrocyclization. The first macrocyclization attempts based on a twofold McMurry coupling were successful but low yielding; the second strategy, profiting from olefin metathesis, provided satisfying yields. Hydrogenation of the olefins resulted in a saturated derivative of similar topology, thereby allowing the interdependence between saturation and physico-chemical properties to be studied. The target structures, including their solid-state structures, were fully characterized. The helical chiral bicycle was synthesized as a racemate and separated into pure enantiomers by HPLC on a chiral stationary phase. Comparison of recorded and simulated chiroptical properties allowed the enantiomers to be assigned.

Automated summary

A new type of Gelander molecule based on an ortho-tetraphenylene core with unique helical chiral bicyclic structure was synthesized and fully characterized. Various strategies, including McMurry coupling and olefin metathesis, were utilized to assemble the target structure, leading to successful synthesis with satisfying yields. The chiral bicyclic molecule was synthesized as a racemate and then separated into pure enantiomers for studying and assigning chiroptical properties.