A “naked eye” and ratiometric chemosensor for cobalt(II) based on coumarin platform in aqueous solution

Abstract A novel ratiometric and colorimetric cobalt(II) chemosensor (HL) based on coumarin platform has been synthesized. It displayed a remarkable (44 nm) red-shift in the absorption spectra upon reaction with Co 2 + , which is easily observed from yellow to red by the naked-eye. Co 2 + could be quantitatively detected in the range of 0–10 μM by both normal and ratiometric absorption spectrometry methods. The detection limit of HL for Co 2 + detection was as low as 0.31 μM.