Abstract

The capability of synthesizing polycyclic arenes containing seven- or eight-member rings is one of the important steps to achieving the imaginary negatively curved carbon allotropes.1 This study presents pre-macrocyclization as a general strategy for the synthesis of negatively curved nanographenes containing multiple heptagons. In this strategy, the critical step is forming a macrocycle precursor containing naphthalene moieties by Yamamoto reaction for the following Scholl reaction. The Scholl reactions of the pre-macrocyclized precursors result in new nanographenes 1–5 (Figure 1), which contain one, two, three, four and six heptagons, respectively. X-ray crystallography, stereodynamics and electronic properties of 1–5 have been studied.

Figure 1. Negatively curved nanographenes 1–5, where the heptagons are highlighted in orange and the C–C bonds formed by Scholl reactions are shown with red bold lines.

References:

1. Pun, S. H.; Miao, Q. Acc. Chem. Res., 2018, 51, 1630-1642.