Pyrrolizine fused bipolar PAHs as a new strategy towards the 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 β-position of the heterocycle with aromatic amines as a donor subunit led to obtaining a set of donor-acceptor architecture-based dyes. Effective narrowing of the HOMO-LUMO gap, along with its tuning by the change in donor strength together with stabilization of π conjugation within the pyrrolizine-NAI core, provided a route to near-infrared (NIR) emission not only in solution (~740 nm) but also in the solid-state (~700 nm).
K. Bartkowski, A. K. Gupta, T. Matulaitis, M. Morawiak, E. Zysman-Colman and M. Lindner, Org. Chem. Front., 2024,
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