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

A simple half-salamo-based fluorescent chemosensor HL based on 3,5-dichlorosalicylic aldehyde can effectively recognize heavy metal Pb2+ ion, and the formed complex L-Pb2+ was used as a novel fluorescent chemosensor for sequentially recognizes cysteine (Cys). The “on-off-on” mode of chemosensors HL and L-Pb2+ achieved by alternately adding Pb2+ and Cys has reached the recycling of chemosensors. Gaussian-09 software was used to optimize the structures of chemosensors HL and L-Pb2+, and the recognition mechanism of chemosensor HL to Pb2+ was further studied by DFT theoretical calculation. In addition, the experimental results of solvent effect, pH range and water sample detection showed that chemosensor has higher practical application efficiency. Recognize of Pb2+ and sequentially recognize of Cys: [Display omitted] •A 3,5-dichlorobenzaldehyde-based chemosensor (HL) is used to detect Pb2+ ion.•HL could distinguish Pb2+ through the turn-on signal from common metal ions.•A new chemosensor (L-Pb2+) formed by HL and Pb2+ ion is used to detect Cysteine (Cys).•The “on-off-on” mode of chemosensors HL and L-Pb2+ achieved by alternately adding Pb2+ and Cys has reached the recycling of chemosensor. 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 × 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 × 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.