Chirality-Embedded Nanographenes.

Abstract

The development of chiral nanographenes has mostly been carried out by bottom-up methods and examples of species developed by the post-modification of nanographenes prepared by top-down methods remain limited. We show that the attachment of chiral functional groups onto the edge of nanographenes generates chirality on the surface. X-ray diffraction analysis and DFT calculations indicate that the chirality of the functional groups is transferred to the surface via steric interactions from the chiral center through the five-membered cyclic imide to the nanographene edge. The exciton coupling between the p-bromophenyl groups confirms that the functional groups are arranged on the armchair edges at distances that permit exciton coupling, which provides information about their relative orientation. These pieces of information help to elucidate the edge structure of nanographenes prepared by top-down methods.