A Family of Highly Fluorescent and Unsymmetric Bis(BF₂) Chromophore Containing Both Pyrrole and N-Heteroarene Derivatives: BOPPY

Abstract

A fundamental, highly fluorescent, and easily accessible scaffold named BOPPY is reported. The use of hydrazine as a bridging linkage between pyrrole and N-heteroarenes enables the binding of two BF 2 units to provide sufficient rigidity of the unsymmetric core skeleton. These resultant unsymmetrical BOPPYs are thus highly fluorescent in their solutions and solid powder states and exhibit high molar absorption coefficients (42200−47000 M −1 cm −1 ), large Stokes shifts, excellent photostability, and insensitivity to pH. More importantly, these BOPPYs showed efficient two-photon absorption in the wide spectral range of 700−900 nm, making them well suited for two-photon fluorescence microscopy imaging in living cells.Letter pubs.acs.org/OrgLett

A Family of Highly Fluorescent and Membrane-Permeable Bis(BF2) Acyl-Pyridinylhydrazine Dyes with Strong Solid-State Emission and Large Stokes Shifts: The BOAPH Fluorophores

“…Among the various fluorophores, bright tetracoordinate boron-containing dyes are of great current interest because the electron-deficient boron endows them with superior tunable electronic and photophysical properties owing to building structural rigidity. − Whereas lots of boranes such as well-known boron dipyrromethene (BODIPY, Figure ) dyes are highly fluorescent in solution, most of them tend to show weak fluorescence in solid states due to self-absorption, which limits their applications. − Recently, bis­(BF 2 ) chromophores as BODIPY analogues, which often have low LUMO energy levels and excellent photostability due to the attached electron-deficient BF 2 groups, have received much attention. − One such popular fluorophore is the recently developed BOPHY (Figure ). The potential of BOPHY as a novel platform was immediately realized, and its derivatives have been used in a range of applications spanning from bioimaging, probes, solar cells, energy-transfer cascades to photocatalyst. − …”

A Family of BODIPY-like Highly Fluorescent and Unsymmetrical Bis(BF2) Pyrrolyl–Acylhydrazone Chromophores: BOAPY

“…In 2014, Ziegler, Nemykin, and co-workers and our group reported the synthesis of highly fluorescent and symmetrical hydrazine-inserted bis­(BF 2 –pyrrole) (BOPHY) chromophores (Figure ) from stable formylpyrrole and hydrazine. They have received diverse applications in fluorescence energy transfer cascades, solar cells, photodynamic therapy, probes, and cellular imaging. − Several novel chromophores containing more than one BF 2 unit were also developed . For example, BOIMPYs and aza-BOIMPYs with N–B–N bridges reported by Werz et al are a family of red-emissive fluorophores. , BF 2 -bridged azafulvene dimers with a N–B–O bridge were developed by Wakamiya et al as a new type of NIR-absorbing dyes .…”

Palladium-Catalyzed Tandem C–C Activation/Cyclization Induced by Carbopalladation of Functionalized Nitriles: Synthesis of Benzo Dipyrromethenes

“…Various methods, which include metal-catalyzed coupling, nucleophilic substitution, and photochemical strategies, have been developed by the modification of the ready-made BODIPY core to synthesize BODIPY derivatives with a long absorption/emission wavelength . The most commonly used strategies include ethynylaryl, aryl, and styryl substitution on the BODIPY cores as well as aromatic ring fusion to expand the conjugated system of BODIPY. Replacing the meso-carbon atom with an aza-nitrogen atom to form an aza-BODIPY is another common method .…”