Globally Aromatic 10-Boratetraoxacorroles: Boron-Doped Macrocyclic Chromophores with Intense Red-to-Near-Infrared Emission
Year: 2026
Type: preprint
Abstract: Neutral, globally aromatic boron-containing macrocycles are exceptionally rare, with the 10-bora-21,22,23,24-tetraoxacorroles reported herein representing only the second class of such compounds known to date, following the 5-bora-21,22-dioxaporphyrin we recently described, and are also the first neutral, globally aromatic boracorroles. Here, we present a furan-based 10-bora-21,22,23,24-tetraoxacorrole and an oxadiborepin-fused derivative thereof. The global aromaticity of both macrocyclic boranes in the neutral state is supported by experimental data and NICS and ACID calculations. They exhibit intense absorption spanning the ultraviolet to near-infrared (NIR) regions of the electromagnetic spectrum. Notably, the novel boracorroles display bright red and red-to-NIR fluorescence, achieving quantum yields more than twice (Φ fl = 35–46%) that of conventional triphenylcorrole (Φ fl = 19%). DFT analysis reveals that the frontier orbital energies are strongly modulated by the meso- B atom, generating a large HOMO to HOMO−1 energy gap and, consequently, markedly enhanced Q-band extinction coefficients arising from the predominantly single-configurational character of the S 0 →S 1 transition (HOMO to LUMO). Incorporation of the BOB bridge in the oxadiborepin-fused derivative significantly stabilizes the LUMO, giving rise to red-shifted absorption and emission alongside distinct electrochemical behavior. In addition, the BOB unit further amplifies the global aromaticity of the boracorrole, underscoring efficient π-conjugation across this heteroatomic bridge.
Source: ChemRxiv
Institution: University of Würzburg
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Funder: Deutsche Forschungsgemeinschaft
OpenAlex ID: W7213467781