A new imidazolium acridine derivative as fluorescent chemosensor for pyrophosphate and dihydrogen phosphate

A new acridine derivative bearing two imidazolium groups has been synthesized. This chemosensor displayed a large fluorescent quenching effect with pyrophosphate and a unique fluorescent enhancement with H2PO4−. The strong (C-H)+⋯X− hydrogen bonding between the imidazolium moieties and anions is the key interaction for the recognition. The association constant of 1 with pyrophosphate was calculated as 4.9×107 M−1.