Interaction of halide and carboxylate ions with 4,5-diacetamidoacridine- 9(10H)-one: Thermodynamics of association and deprotonation events

4,5-Diacetamidoacridine-9(10H)-one was prepared, and its interactions with halide and benzoate anions were studied using a combination of NMR, fluorescence, and isothermal titration calorimetry experiments. Whereas chloride and bromide exhibited simple association, both fluoride and benzoate exhibited initial entropy-driven association followed by an enthalpically favorable deprotonation of the receptor by a second equivalent of the anion.