Optical Cu2+ probe bearing an 8-hydroxyquinoline subunit: High sensitivity and large fluorescence enhancement

► A new fluorescent and colorimetric probe RCu1 with ultra-sensitivity (detection limit is 4.7 nM (3σ)) was developed. ► RCu1 showed greatly large fluorescence enhancement (F/F0 > 1000) in the presence of Cu2+ in aqueous media. ► The detection mechanism was proved by TOF-MS, FT-IR, 1H NMR and Gaussian calculations. ► Based on the outstanding recognition ability of RCu1 toward Cu2+, an analytical procedure was developed for Cu2+-determination in natural water samples and soil sample.