A highly selective and sensitive half-salamo-based fluorescent chemosensor for sequential detection of Pb(II) ion and Cys

A half-salamo-based fluorescent chemosensor HL based on 3,5-dichlorosalicylaldehyde was developed. Sensor HL showed a single selectivity for heavy metal Pb2+ ion by "on-turn" fluorescence in various common metal ions. After forming a 2 : 1 type complex with Pb2+ ion, the minimum detection limit (LOD) of HL for Pb2+ ion was calculated as 5.65 x 10(-8) M. In addition, the complex formed by HL and Pb2+ ion was used as a new chemosensor L-Pb2+ for further recognition of cysteine (Cys), thereby releasing HL. The minimum detection limit (LOD) of Cys for L- Pb2+ was calculated as 3.80 x 10(-7) M. The "on-off-on" mode of chemosensors HL and L- Pb2+ achieved by alternately adding Pb2+ and Cys has reached the recycling of chemosensors.