A chemosensor with a paddle structure based on a BODIPY chromophore for sequential recognition of Cu(2+) and HSO(3)(−)

In this study, a highly selective chemosensor ML based on a BODIPY fluorescent chromophore was synthesized for sequential recognition of Cu(2+) and HSO(3)(−) in a CH(3)OH/H(2)O (99 : 1 v/v) system, which contained three recognition sites and its structure characterized by (1)H NMR, (13)C NMR and ESI-HR-MS. The sensor ML showed an obvious “on–off” fluorescence quenching response toward Cu(2+) and the ML-Cu(2+) complex showed an “off–on” fluorescence enhancement response toward HSO(3)(−). The detection limit of the sensor ML was 0.36 μM to Cu(2+) and 1.4 μM to HSO(3)(−). In addition, the sensor ML showed a 1 : 3 binding stoichiometry to Cu(2+) and the recovery rate of ML-Cu(2+) complex identifying HSO(3)(−) could be over 70%. Sensor ML showed remarkable detection ability in a pH range of 4–8.