A coumarin-based turn-on chemosensor for selective detection of Zn(II) and application in live cell imaging.

A 2-oxo-2H-chromene-3-carbohydrazide (CHB) was synthesized by the reaction of salicylaldehyde with diethyl malonate and hydrazine hydrate. The recognition behaviors of CHB to Zn2+ were investigated and the results showed that CHB exhibits well selectivity and sensitivity to Zn2+ with fast response in PBS (pH = 7.24, 60% DMF), the co-existed cations and anions could not interfere the recognition between CHB and Zn2+. Besides, the detection limit of CHB for Zn2+ was calculated to be 0.95 μM. Furthermore, DFT, EI-MS data and Job's plot were applied for determining the sensing mechanism of CHB with Zn2+ and the results showed that a type of 2:1 complex was formed between CHB and Zn2+ with the binding constant was 1.32 × 104 M-2. At last, probe CHB was successfully applied for the imaging of Zn2+ in living cells.