A TPA-caged precursor of (imino)coumarin for "turn-on" fluorogenic detection of Cu(.)

We strategize to utilize the precursors of (imino)coumarin fluorophores to deliver novel reactive Cu(+) probes, where tris[(2-pyridyl)-methyl] amine (TPA) works as a reactive receptor towards Cu(+). To verify this strategy, CP1, a representative probe and relevant sensing behaviors towards Cu(+) are presented here. CP1 features good solubility and fast response for monitoring labile copper in aqueous solution and live cells. The sensing mechanism of CP1 is determined by HPLC titration and mass spectrometric analysis. The probe CP1 exhibits a 60-fold fluorescence enhancement and a detection limitation of 10.8 nM upon the detection of Cu(+). CP1 is further applied for imaging labile copper in live cells. This work provides a starting point for future development of Cu(+) probes, based on in situ formation of (imino)coumarin scaffolds, as well as their further investigations of copper signaling and biological events.