A novel AIE-active imidazolium macrocyclic ratiometric fluorescence sensor for pyrophosphate anion

An imidazolium bridged macrocyclophane was synthesized as a ratiometric fluorescence sensor with aggregation-induced emission (AIE) characteristic to detect pyrophosphate anion with high selectivity among various anions. In the presence of zinc ion, macrocyclophane can form aggregates through complexation with pyrophosphate anion and emit ratiometric fluorescence, resulting from an enhancement in its aggregate-state emission and a reduction in its monomer emission. This AIE-active macrocycle showed great potential as a ratiometric fluorescence receptor. The fluorescence of an imidazolium macrocycle can be switched from monomer emission to aggregate emission in the presence of pyrophosphate anion and zinc ion, which can be used as a ratiometric fluorescence sensor for pyrophosphate anion in water.