A C3-symmetric colorimetric anion sensor bearing hydrazone groups as binding sites

Tris-hydrazone (1) functioned as a colorimetric chemosensor for a variety of anions such as F(-), AcO(-) and H(2)PO(4)(-). The anion binding could be easily detected by naked-eye according to color changes. The high binding ability of the receptor 1 to anions was further investigated by UV-vis absorption spectroscopy in DMSO. The results of job plot of the receptor 1 with different anions demonstrated that the stoichiometry of the complex between 1 and F(-) was 1:1 (1:anion) and the stoichiometry of the other complexes studied was 1:3 (1:anion).