Quinoxaline−Imidazolium Receptors for Unique Sensing of Pyrophosphate and Acetate by Charge Transfer.

Quinoxaline derivatives (1−4) bearing two imidazolium moieties are found to strongly bind anions and show unique charge-transfer fluorescent responses to pyrophosphate and acetate, whereas they show excimer formation with other anions. Anion-binding studies are investigated with fluorescence and 1H NMR analysis, single-crystal X-ray analysis, and theoretical calculations. [ABSTRACT FROM AUTHOR]