A turn-on fluorescent anion receptor based on N,N′-di-β-naphthyl-1,10-phenanthroline-2,9-diamide

A simple turn-on fluorescent anion chemosensor with amide moiety as binding sites was designed, synthesized and characterized. Binding ability of the receptor 1 with anions was evaluated through the fluorescence titration in DMSO and the 1H NMR titration in DMSO-d6 and coordination of anions to 1 led to a visible enhancement in fluorescence intensity. The fluorescence enhancement could be explained on the basis of two signaling transduction mechanisms: (1) inhibition of a photoinduced electronic transfer (PET) mechanism and (2) anion-induced increase of the rigidity of the host molecules. In addition, the results of 1H NMR titrations suggested that a host–guest hydrogen-bonding complex with an association constant Kass=7379 mol−1 L was formed between 1 and F− and the mode of host–guest interactions was provided.