Diarenofuran[<i>b</i>]-fused BODIPYs: One-Pot S_NAr-Suzuki Synthesis and Properties

We present a streamlined methodology that integrates regioselective tetrahalogen-BODIPY and <i>o</i>-hydroxyphenylboronic acid in a one-pot process, leveraging S_NAr nucleophilic substitution in conjunction with Suzuki coupling to afford diarenofuran [<i>b</i>]-fused BODIPYs (<b>DBFB1</b>-<b>9</b>) with commendable yields (85-95%) and short reaction times (0.5-1.0 h). X-ray structure analyses of <b>DBFB5</b>,<b>7-9</b> elucidate that these diarenofuran[<i>b</i>]-fused BODIPYs adopt a "butterfly" conformation, maintaining a highly rigid planarity. A comprehensive examination of the spectroscopic and electrochemical properties of these diarenofuran[<i>b</i>]-fused BODIPY derivatives, incorporating various substituents, reveals intriguing characteristics, including pronounced absorption and emission in the near-infrared region (NIR), elevated fluorescence quantum yields (Φ_F = 75-89% in dichloromethane), and tunable HOMO-LUMO levels. Remarkably, compared to <b>DBFB1</b>-<b>8</b>, <b>DBFB9</b> possesses a large extended π-conjugated system, resulting in significant red shifts in its absorption and emission maxima, reaching 623 and 635 nm, respectively, and a reduced HOMO-LUMO gap. Despite this substantial structural expansion, <b>DBFB9</b> maintains a surprisingly high fluorescence quantum yield (Φ_F = 80%), underscoring its exceptional photophysical performance and strong potential for applications requiring efficient NIR emission and robust fluorescence retention.