Reaction-based probes for Co(II) and Cu(I) with dual output modes: fluorescence live cell imaging

Two new reaction-based molecular probes ResCo and ResCu are reported for the selective colourimetric and fluorometric detection of Co2+ and Cu+, respectively. The receptor in these probes differs by a single metal coordinating site combined with resorufin as a common reporter dye, which exhibit visible absorption and emission in the longer wavelength regions. Co2+- and Cu+-mediated oxidative benzylic ether (C-O) bond cleavage in ResCo and ResCu, respectively, releases resorufin dye which offer 'switch-on' fluorometric and ratiometric visible absorption (colourimetric) in a reducing aqueous environment. Reaction-based selective detection of Co2+ and Cu+ is demonstrated in the presence of all other competing metal ions. Submicromolar concentration of Co2+ and Cu+ can be easily detected through dual signaling (fluorometric and colourimetric) pathways. The probes ResCo and ResCu are employed for 'switch-on' fluorescence live cell imaging of Co2+ and Cu+, respectively, in HEK293T cells.