Dual Emission, Aggregation, and Redox Properties of Boron Difluoride Hydrazones Functionalized with Triphenylamines

Abstract

Abstractπ‐Conjugated molecular materials often exhibit interesting photoluminescence, redox, and optoelectronic properties that grant them utility as light‐harvesting materials in solar cells, as the emissive component of organic light‐emitting diodes, and as fluorescence sensors. Preparing dye conjugates by appending multiple dyes together to generate π‐conjugated molecules is a common strategy to enhance the properties of these materials as it often imparts traits that cannot be achieved by the building blocks independently. Herein, we report molecular materials that incorporate boron difluoride hydrazone (BODIHY) and triphenylamine (TPA) units that exhibit charge‐transfer character, dual‐emission, and aggregation‐induced emission. The title compounds have low‐energy absorption bands (λabs=455–493 nm) that are red‐shifted relative to BODIHYs with smaller π‐systems and exhibit dual‐emission in the solution, solid, and aggregate states. TPA–BODIHY (donor‐acceptor) conjugates show multiple reversible redox events and, in combination, the data presented herein indicate that there is electronic communication throughout the donor‐acceptor and acceptor‐donor‐acceptor π‐systems. These results are rationalized with the use of computational chemistry and solid‐state structural analysis. This study provides new opportunities for the design of molecular materials that are comprised of redox‐active photoluminescent dyes, including BODIHY, and their potential applications.