Using pyrrolizine-fused bipolar PAHs as a new strategy towards efficient red and NIR emissive dyes

We report the synthesis and characterization of the first pyrrolizine-embedded PAH systems. The bipolar core, based on a naphthalimide and indole fusion, was successfully synthesized through a one-pot cascade of Suzuki/Boc deprotection/Buchwald-Hartwig transformations. A facile post-functionalization of the unoccupied beta-position of the heterocycle with aromatic amines as donor subunits led to a set of donor-acceptor architecture-based dyes. Effective narrowing of the HOMO-LUMO gap, along with its tuning by changing donor strength together with stabilization of pi conjugation within the pyrrolizine-NMI core, provided a route to near-infrared (NIR) emission not only in solution (similar to 740 nm) but also in the solid-state (similar to 700 nm). We report the synthesis and characterization of the first pyrrolizine-embedded PAH systems which exhibited red and NIR emission in solution and solid-state.

Automated summary

We report the synthesis and characterization of the first pyrrolizine-embedded PAH systems which exhibited red and near-infrared emission in solution and solid-state.