Synthesis and properties of contorted hexabenzocoronenes with arylamino groups

Abstract

Novel classes of contorted hexabenzocoronenes (c-HBCs) which exhibit a doubly concave configuration were synthesized by using hexabenzocoronene as bridge ligand and diphenylamine/triphenylamine as the redox-active termini. Although the analysis of the crystal structures of tri-di(4-methoxyphenyl)amino-substituted HBC (1), trimethoxy-substituted HBC (3) and tri(triphenylamine)-substituted HBC (4) show that the peripheral modified arylamine groups have a certain influence on the interaction force between molecules, the results of UV–vis absorption and fluorescence emission spectra indicate that these arylamine-modified hexabenzocoronenes have similar photophysical properties, which are primarily regulated by the c-HBC center. Subsequent electrochemical tests found that these compounds have multi-step redox process, and there is a certain degree of overlap between the arylamine and arylamine or between the arylamine and the bridge (c-HBC) during the oxidation process. Combining the UV-vis-NIR spectroelectrochemistry with the density functional theory (DFT) calculations, we further explored the electronic characters of the neutral and one-electron oxidation states of tri-di(4-methoxyphenyl)amino-substituted HBC (1), trimethoxy-substituted HBC (3) and tri(triphenylamine)-substituted HBC (4).