Synthesis, electronic properties, and self-assembly of an alkylated dibenzo(biscorannulene)

Abstract

The synthesis and properties of novel aromatic compounds containing fully-conjugated multi-corannulenes are a subject of intense interest. We herein report the synthesis, electronic properties, and self-assembly of alkylated dibenzo(biscorannulene) 1. The properties of 1 are compared with those of the reference compound dibenzocorannulene 2. While the influence of the number of corannulene units on the electronic properties and aromaticity is limited based on UV-vis and emission spectra, electrochemistry, and the results of DFT simulations, the self-assembly behavior is different between molecules of 1 and 2. In ¹H NMR spectra in CDCl₃, both compounds show concentration-dependent changes in the chemical shifts of the aromatic hydrogen signals. This indicates self-association, in which the association constant of 1 is greater than that of 2 assuming a monomer–dimer equilibrium. In the crystalline phase, molecules of 1 adopt a parallel-stacked dimer structure through a concave–convex interaction mode, while molecules of 2 form a different structure through a concave–concave interaction mode. DFT simulations of the dimers with different configurations support the increased van der Waals interactions between two fused corannulene units in the stacking geometry. The present results expand the design strategies for gaining control over the organization and functionality of π-conjugated molecules that contain multiple corannulene units.