Pyridoxal-thiosemicarbazide: its anion sensing ability and application in living cells imaging

A new anion selective chemosensor L was derived through a direct condensation reaction between pyridoxal and thiosemicarbazide. Sensor L showed selective recognition and sensing ability towards F- and AcO- anions through a naked-eye detectable color change from colorless to light yellow, appearance of a new charge transfer absorption band at 404 nm and significant turn-on fluorescence at 506 nm. The detection limit of L as a fluorescent 'turn-on' sensor for the analysis of F- and AcO- was estimated to be 0.10 mu M. The anion sensing mechanisms of L was supported by H-1 NMR and DFT results. Finally, the cytotoxicity effect of L and its ability to image intracellular F- ions in the living HeLa cells was investigated.