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

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 BF2 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.