Synthesis, Crystal Structure, and the Deep Near-Infrared Absorption/Emission of Bright AzaBODIPY-Based Organic Fluorophores

Annularly fused azaBODIPY-based organic fluorophores (HBPs <b>2</b>) containing up to 13 aromatic ring fusions were synthesized by a Suzuki coupling reaction with bromoazadipyrromethenes and a subsequent regioselective oxidative ring-fusion reaction. X-ray analysis indicates almost planar dipyrrin cores for all crystals but overall curved or “wave” conformations for those HBP dyes. These molecules exhibit unique structural and physical properties including excellent spectral selectivity (negligible absorption between 300 and 700 nm), sharp near-infrared (NIR) absorption (up to 878 nm) and emission (up to 907 nm), large extinction coefficient (up to 4.5 × 10⁵ M^–1 cm^–1), and excellent photostabilities

Synthesis, Structure, and Properties of β‑Vinyl Ketone/Ester Functionalized AzaBODIPYs from FormylazaBODIPYs

Postfunctionalization of azaBODIPY (the BF₂ complex of azadipyrromethene) is highly desirable due to the strong tunable absorption bands at wavelengths above 650 nm and the wide-ranging applications of this class of dyes in biomedicine and materials science. Currently available postfunctionalization methods for this class of dyes have been limited to the Pd-catalyzed coupling reactions on β-halogenated (brominated or iodinated) azaBODIPY platforms. In this work, we report a new strategy for the facile postfunctionalization of the azaBODIPY chromophore with various vinyl ketone and vinyl esters based on a Wittig reaction on our previously developed β-formylazaBODIPYs and our recently developed β-bromo-β′-formylazaBODIPYs. Our strategy uses easily accessible starting materials and mild reaction conditions. It is highly compatible with various common phosphonium ylides (aliphatic, aromatic, and ester substituted ones). These resultant bromo-containing β-vinyl ketone/ester functionalized azaBODIPYs are potential photosensitizers and can be further functionalized via coupling reactions. The ester groups on some of these resultant azaBODIPYs can be further hydrolyzed to achieve the desired water solubility and conjugate with the biomolecule and solid surface

Synthesis, Structure, and Properties of β‑Vinyl Ketone/Ester Functionalized AzaBODIPYs from FormylazaBODIPYs

Postfunctionalization of azaBODIPY (the BF₂ complex of azadipyrromethene) is highly desirable due to the strong tunable absorption bands at wavelengths above 650 nm and the wide-ranging applications of this class of dyes in biomedicine and materials science. Currently available postfunctionalization methods for this class of dyes have been limited to the Pd-catalyzed coupling reactions on β-halogenated (brominated or iodinated) azaBODIPY platforms. In this work, we report a new strategy for the facile postfunctionalization of the azaBODIPY chromophore with various vinyl ketone and vinyl esters based on a Wittig reaction on our previously developed β-formylazaBODIPYs and our recently developed β-bromo-β′-formylazaBODIPYs. Our strategy uses easily accessible starting materials and mild reaction conditions. It is highly compatible with various common phosphonium ylides (aliphatic, aromatic, and ester substituted ones). These resultant bromo-containing β-vinyl ketone/ester functionalized azaBODIPYs are potential photosensitizers and can be further functionalized via coupling reactions. The ester groups on some of these resultant azaBODIPYs can be further hydrolyzed to achieve the desired water solubility and conjugate with the biomolecule and solid surface

Direct Synthesis of Dipyrrolyldipyrrins from S_NAr Reaction on 1,9-Dihalodipyrrins with Pyrroles and Their NIR Fluorescence “Turn-On” Response to Zn²⁺

A set of dipyrrolyldipyrrins have been efficiently synthesized from a direct S_NAr reaction on 1,9-dihalodipyrrins with pyrroles and show intense absorption in the NIR region (650–800 nm, as HCl salts). Substituents on both 1,9-dihalodipyrrins and pyrroles greatly affected the reactivity of this S_NAr reaction and the absorption properties of the resultant dipyrrolyldipyrrins. These dipyrrolyldipyrrins show sensitive and selective “turn-on” fluorescence response toward Zn²⁺

[<i>a</i>]‑Phenanthrene-Fused BF₂ Azadipyrromethene (AzaBODIPY) Dyes as Bright Near-Infrared Fluorophores

A new substitution pattern of BF₂ azadipyrromethene (azaBODIPY) dyes was obtained by phenanthrene fusion through a key palladium-catalyzed intramolecular C–H activation reaction. These [<i>a</i>]-phenanthrene-fused azaBODIPYs have a near planar structure of the phenanthrene-fused azadipyrromethene core in the crystalline state. The chromophore absorbs (log ε > 5) and fluoresces (ϕ = 0.32–0.38) strongly above 700 nm with excellent photostability and may be used as an attractive bright NIR bioimaging agent

Synthesis, Properties, and Semiconducting Characteristics of BF₂ Complexes of β,β-Bisphenanthrene-Fused Azadipyrromethenes

Three novel π-extended BF₂ complexes of β,β-bisphenanthrene-fused azadipyrromethenes containing nine fused rings have been synthesized on the basis of a tandem Suzuki coupling reaction on readily available 2,6-dibromoazaBODIPYs followed by an intramolecular oxidative aromatic coupling mediated by iron­(III) chloride. These resultant BF₂ complexes exhibit strong absorption (extinction coefficients up to 2.4 × 10⁵ M^–1 cm^–1) and emission in the near-infrared (NIR) range (790–816 nm) with excellent photo and thermal stabilities. The hole mobility of the thin-film field-effect transistors of these dyes fabricated by a solution process reaches up to 0.018 cm² V^–1 s^–1