A novel terephthalaldehyde based turn-on fluorescent chemosensor for Cu2+ and its application in imaging of living cells.

A new terephthaldehyde-based chemosensor 1 bearing an aminophenol recognition unit has been synthesized and applied to the fluorescent sensing of metal ions. Molecular system 1 acts as a highly selective and sensitive fluorescence turn-on sensor for Cu2+. The sensing mechanism has been explored. It is proposed that Cu2+ binds with the imine and hydroxyl moiety of 1 in 1 : 2 binding stoichiometry, thereby enhancing the fluorescence at 386 nm. The detection limit and association constant (Ka) of 1 with Cu2+ were found to be 0.62 µM and 6.67 × 104 M-1, respectively. Chemosensor 1 has shown excellent specificity towards Cu2+ and has been successfully applied to the determination of Cu2+ in live L929 cells.

A new Schiff base as a turn-off fluorescent sensor for Cu2+ and its photophysical properties.

A new Schiff base receptor 1 was synthesized and its photophysical properties were investigated by absorption, emission and excitation techniques. Furthermore, its chromogenic and fluorogenic sensing abilities towards various metal ions were examined. Receptor 1 selectively detects Cu2+ ion through fluorescence quenching and detection was not inhibited in the presence of other metal ions. From fluorescence titration, the limit of detection of receptor 1 as a fluorescent 'turn-off' sensor for the analysis of Cu2+ was estimated to be 0.35 µM.

Highly selective optical and reversible dual-path chemosensor for cyanide detection and its application in live cells imaging.

A new biocompatible fluorescent receptor 1 was synthesized by conjugating diaminomaleonitrile (DMN) with benzothiazole unit, and characterized by single X-ray. In DMF/water (1:1, v/v), the receptor 1 showed a selectivity turn-on fluorescence at 517nm in the presence of CN-. Receptor 1 showed a detection limit down to 0.16µM without any interference from other tested anions. The reversibility and reusability of 1 for the detection of CN- ion was also tested for five cycles indicating the probe 1 could be used in a reversible manner. Importantly, the receptor 1 showed excellent cells viability and was successfully applied for the detection of CN- in live mouse fibroblast cells L929 cells.