Recognition of pyrophosphate anion in aqueous solution using the competition displacement method

A chiral compound 1 derived from bis(2-pyridinmethyl)amine was designed and synthesized, the dinuclear complexes 1-2Zn2+ and 1-2Cu2+ were formed through binding with metal ions (Zn2+, Cu2+). It was found that both complexes could be used to recognize anions in aqueous solution (10 mM HEPES buffer); pyrocatechol violet (PV) was used as the UV–vis indicator to monitor this binding process. Both ternary complexes 1-2Zn2+ (PV) and 1-2Cu2+ (PV) displayed the selective recognition abilities towards pyrophosphate (PPi) anions much better than other anions such as phosphate (Pi), ATP, ADP, AMP, acetate and halogen anions. The binding results were further confirmed by the circular dichroism (CD) spectrum.