Dibenzo [a, g] corannulene-phenoxazine dyads: Facile synthesis and optoelectronic properties

Abstract

Corannulene has a peculiar topology, while phenoxazine (PXZ) features extraordinary optoelectronic properties. In this study, two dibenzo [a, g] corannulene-phenoxazine dyads, BBC-C-PXZ and BBC-N-PXZ, connected via C–C and C–N bonds, respectively, were successfully prepared using PXZ as an electron donor and dibenzo [a, g] corannulene (BBC) as an electron acceptor. Photoelectrical properties of the compounds were studied using UV–vis absorption, luminescence spectroscopy, electrochemical tests and theoretical calculations. Both dyads showed Curve-Twist intramolecular charge transfer (C-TICT) in solution and aggregated state, which could be explained by the BBC-C-PXZ concave-convex crystal packing mode. They further exhibited moderate to good singlet oxygen quantum yields, the BBC-N-PXZ was 42.3% in toluene and BBC-C-PXZ was only 14.3% in n-hexane. The BBC-N-PXZ (connected by the C–N bond) exhibited contrasting reversible and anti-fatigue “turn-on” mechanochromic behavior, which displayed a blue shift under external stimulation, while the BBC-C-PXZ (linked by the C–C bond) did not exhibit this phenomenon. Analyses of the D-A (donor-acceptor) dyad systems revealed that the introduction of curved polycyclic aromatic hydrocarbons and diversified linkage positions result in unique optical and electrical properties of materials, and it provides new advances and breakthroughs in the design of organic electronic materials.