Selective fluorometric detection of pyrophosphate and stringent alarmone with copper(II)–2,6-bis(2-benzimidazolyl)pyridine complex

Pyrophosphate (PPi) is involved in lots of anabolism and bioenergetic processes in organisms and possesses important biological functions so that its detection is very significant. Here, we developed a selective fluorometric detection method for PPi with a copper(II) complex of 2,6-bis(2-benzimidazolyl)pyridine (bbimp), and then applied it to the detection of bacterial alarmone ppGpp. bbimp has the fluorescence emission at 395 nm, but the bbimp–Cu2+ complex is hardly fluorescent because the intrinsic fluorescence of bbimp is effectively quenched by Cu2+. With the addition of PPi, however, the fluorescence emission of bbimp turns on with a 2 nm red-shift, and has a linear relationship with PPi in the range of 3–90 μmol/L. This method has good selectivity for PPi over other anions especially those phosphate-containing anions such as ATP, UTP, CTP, GTP, GDP, and PO43−.

► bbimp as the ligand is easily synthesized through one step.
► We develop a fluorescent turn-on detection method for PPi with bbimp–Cu2+ complex.
► The method has good selectivity for PPi against other anions such as nucleotides.
► We apply the bbimp–Cu2+ complex to the detection of bacterial alarmone ppGpp.