Lemniscular [16]Cycloparaphenylene A Radially Conjugated Figure-Eight Aromatic Molecule

Kabali Senthilkumar (1) , Mateusz Kondratowicz (1) , Tadeusz Lis (1) , Piotr J Chmielewski (1) , Joanna Cybińska (1) , José L Zafra (2) , Juan Casado (2) , Thomas Vives (3) , Jeanne Crassous (3) , Ludovic Favereau (3) , Marcin Stępień (1)

1 Uniwersytet Wroclawski
2 Universidad de Málaga [Málaga] = University of Málaga [Málaga]
3 ISCR - Institut des Sciences Chimiques de Rennes

A cycloparaphenylene-based molecular lemniscate (CPPL) was obtained in a short synthesis involving masked p-phenylene equivalents. The strained figure-eight geometry of CPPL is sustained by the incorporated 9,9'-bicarbazole subunit, which also acts as a stereogenic element. The shape of the distorted [16]cycloparaphenylene nanohoop embedded in CPPL is accurately approximated with a Booth lemniscate. The structure of CPPL, investigated using NMR and Raman spectroscopic methods, revealed strain-dependent features, consistent with the variable curvature of the ring. The electronic and optical properties of CPPL combine features more characteristic of smaller cycloparaphenylenes, such as a reduced optical bandgap and red-shifted fluorescence. CPPL was resolved into enantiomers, which are configurationally stable and provide strong chiroptical responses, including circularly polarized luminescence.

Domains: Chemical Sciences; Organic chemistry

Kabali Senthilkumar, Mateusz Kondratowicz, Tadeusz Lis, Piotr J Chmielewski, Joanna Cybińska, et al.. Lemniscular [16]Cycloparaphenylene A Radially Conjugated Figure-Eight Aromatic Molecule. Journal of the American Chemical Society, 2019, 141 (18), pp.7421-7427. ⟨10.1021/jacs.9b01797⟩. ⟨hal-02120740⟩