The anion recognition properties of Schiff base or its reductive system based on 2,2′-bipyridine derivatives

Two novel artificial receptors, 2,2′-bipyridine derivatives containing phenol group, have been designed and synthesized. The interaction of the receptors containing Schiff base or its reductive system with biologically important anions was determined by UV–vis and 1H NMR titration experiments. Results indicate that receptors 1 and 2 show the strong binding ability for dihydrogen phosphate (H2PO4−), fluoride (F−), acetate (AcO−) and almost no binding ability for chloride (Cl−), bromide (Br−), iodide (I−). At the same time, the strongest binding ability of receptor 1 for H2PO4− among studied anions is not influenced by the existence of other anions; as well as receptor 2 for F−. In addition, the binding ability of receptor 1 (Schiff base system) with various anions is stronger than that of receptor 2 (the reductive Schiff base system) due to the difference of electronic effect.