Corannulene-based nanographene containing helical motifs

Abstract

The synthesis and structural analyses of corannulene-PAH hybrids 1 with a [4] helicene subunit and 2 with a [7] helicene subunit have been reported. The structures of 1 and 2 were confirmed by single-crystal X-ray diffraction. The experimental data in combination with theoretical calculations revealed that the terminal ring of helicene and the π-surface of the corannulene unit of 2 adopt a convex conformation, which is a more stable conformation. Meanwhile, 2 displays a red-shift in fluorescence emission but a shorter fluorescence lifetime, in comparison with 1. The optical resolution of 2 was successfully carried out by chiral HPLC, offering enantiopure P-2 and M-2, which were further characterized by CD and CPL spectroscopy.