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RESEARCH PRODUCT

Synthesis, stability and spectral behavior of fluorogenic sulfone-pyronin and sulfone-rosamine dyes

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International audience; The first synthesis of sulfone-pyronin and sulfone-rosamine dyes bearing optically tunable primary amino groups (acting as fluorogenic centers) is presented. Sulfone analogs of xanthene-based fluorophores have recently been highlighted as a new class of near-infrared (NIR) fluorescent dyes (Liu et al. ACS Appl Mater Interfaces 2016; 8(35):22953-62), and the availability of fluorogenic derivatives is essential for the rapid construction of “turn-on” reactive probes for chemoselective bioimaging. However, these fluorescent anilines have been found to be unstable in aqueous physiological conditions due to the marked electrophilicity of their meso-position and hence its propensity to undergo nucleophilic attack by a water molecule or a hydroxyde anion. Further investigations have helped us to determine the acidic pH range at which the sulfone-rosamine 2 is fully-stable and a complete assessment of the photophysical properties could be performed. Its pro-fluorescent character and utility were then proved by the preparation and in vitro enzymatic activation of a penicillin G acylase (PGA) sensitive fluorogenic probe.