Fluorescent Sensing of Pyrophosphate and Bis-carboxylates with Charge Neutral PET Chemosensors^†

The fluorescent photoinduced electron transfer (PET) chemosensors 2 and 3 were designed for the recognition of anions possessing two binding sides such as dicarboxylates and pyrophosphate; the anion recognition in DMSO takes place through the two charge neutral thiourea receptor sites with concomitant PET quenching of the anthracene moiety. The anion binding of acetate, phosphate, and pyrophosphate to 2 and 3 was also evaluated by using ¹H NMR in DMSO-d₆.