New fluorescent photoinduced electron transfer chemosensor for the recognition of H2PO4-.

[structure: see text] The fluorescent chemosensor 1 bearing two imidazolium groups at the 1,8-position of anthracene has been designed for the recognition of anions through the (C-H)(+)- - -X(-) hydrogen bond formation. As unique tweezer-like binding of 1 with anions is predicted by the ab initio calculations, strong anion-binding properties of chemosensor 1 are demonstrated by using fluorescence as well as (1)H NMR.