Simultaneous Near‐Infrared and Two‐Photon In Vivo Imaging of H2O2 Using a Ratiometric Fluorescent Probe based on the Unique Oxidative Rearrangement of Oxonium

A new ratiometric fluorescent H₂ O₂ probe, benzopyrylium-coumarin (BC), is designed by using an oxonium moiety as the unique H₂ O₂ response site. The BC probe exhibits an extremely large emission shift of 221 nm in response to H₂ O₂ , and is successfully applied for the simultaneous near-infrared and two-photon imaging of H₂ O₂ in living cells, mouse-liver tissues, and zebrafish.