Modular Far-Red Emissive Fluorophores with Large Stokes Shift for Fluorescence Microscopy

Abstract

Here, we report a series of donor (D)–acceptor (A) type fluorophores characterized by far-red emissions and a large Stokes shift. These fluorophores were synthesized through a modular strategy. Specifically, the donor moiety was constructed by introducing a dialkylamino group via a Pd-catalyzed Buchwald–Hartwig cross-coupling reaction, and the acceptor unit was formed through oxazolone Knoevenagel condensation with various aromatic aldehydes. Systematic characterization reveals that these fluorophores possess two key photophysical properties: (1) a pronounced Stokes shift (>90 nm) and (2) exceptional photostability. Furthermore, cellular staining experiments suggest their potential applicability for mitochondrial targeting.