The anion recognition properties of hydrazone derivatives containing anthracene

A series of artificial receptors, hydrazone derivatives containing anthracene, have been designed and synthesized. The interaction of these receptors with biologically important anions was determined by UV-vis, fluorescence and 1H NMR titration experiments and theoretical investigation. Results indicate that the receptor (1) without NO2 shows no binding ability for various anions. The other receptors (2 and 3) show the highest binding ability for acetate (AcO-) among studied anions (fluoride (F-), dihydrogen phosphate (H2PO4-), chloride (Cl-), bromide (Br-), iodide (I-)); and the binding ability for AcO- is not interfered by the existence of other anions. The additions of AcO-, F- and H2PO4- can arouse different degrees of fluorescence quenching. 1H NMR titration shows that the interaction between the receptor 2 and F- firstly depends on the hydrogen-bond formation; later the interacted site NH is deprotonated and the added F- forms hydrogen bond with the near CH in Schiff base. Moreover, visual color changes accompany guest binding, enabling this system to act as colorimetric anion sensors.