Ortho-phenylenediamine-based open and macrocyclic receptors have been designed and synthesized. The open receptor 1 and the macrocyclic receptor 2 fluorimetrically distinguish H2PO4− from the other anions examined in CH3CN with appreciable binding constant values. As practical applications, they are also sensible to nucleotides in aq. CH3CN (1: 1, v/v). The receptor 1 shows significant emission change upon complexation of ATP and ...