Rational Design of A Two-photon Ratiometric Fluorescent Probe for Hypochlorous Acid with A Large Stokes Shift.

By introducing tetrahydroquinoxaline group as the electron donor to enhance intramolecular charge transfer effect, we deliberately designed a coumarin derivative, TQC-HClO, to serve as a two-photon ratiometric fluorescent probe for imaging hypochlorous acid in cells and zebra fish with good sensitivity and high selectivity. TQC-HClO displayed an obvious two-photon absorbance cross-section (over 100 GM in 800-840 nm), large Stokes shifts (159 nm to 173 nm) and a ratiometric fluorescence change from orange (λmaxEm = 583 nm) to red (λmaxEm = 650 nm) in response to hypochlorous acid.