A C156 Molecular Nanocarbon: Planar/Rippled Nanosheets Hybridization

A novel hybrid nanocarbon consisting of one rippled and two planar nanosheets has been synthesized and characterized. Two meso pairs of [5]helicenes are formed along the long molecular axis of the hybrid to connect rippled and planar subunits, leading to a stable conformation. It is shown that the hybrid possesses the individual electronic properties of the rippled and planar subunits. Compared to the rippled subunit, such hybrid has a better geometric match to C₆₀ and complexes with C₆₀ in a 1 : 1 stoichiometry, with the association constant on the order of 10⁵ M^-1. The hybrid displays unusual anti-Kasha fluorescence emission. The transient absorption spectroscopy revealed that the singlet fission (SF) from higher level singlet excited states (S_n) is operative in the film of the hybrid.