A novel fluorescent sensor derived from benzimidazo[2,1-a]benz[de]isoquinoline-7-one-12-carboxylic acid for Cu2+, Cd2+ and PPi

• L has a great selectivity towards Cu2+ and Cd2+ in acetonitrile-H2O buffer solution.
• The new formed [Cu(L)] and [Cd(L)] complexes could be further used as PPi sensors.
• The sensing mechanisms of L towards Cu2+ and Cd2+ have been verified by Gaussian 09.

Fluorescent sensor of N,N-bis(pyridin-2-ylmethyl)benzimidazo[2,1-a]benz[de]isoquinoline-7-one-12-carboxamide (L) was prepared. L not only showed fluorescence quenching towards Cu2+ with a detection limit of 1.2 × 10−8 mol/L in acetonitrile–H2O (9:1) buffer solution, but also showed fluorescence turn-on response with a blue shift towards Cd2+ with a detection limit of 1.5 × 10−7 mol/L in the same condition. Moreover, the new formed [Cu(L)] complex was found to act as a selective ‘turn-on’ fluorescent probe for pyrophosphate (PPi) with detection limit of 8 × 10−9 mol/L, and [Cd(L)] complex was found to act as a selective colorimetric fluorescent probe for PPi with detection limit of 2.4 × 10−8 mol/L. Such behaviors confirmed L could be applied as fluorescent sensor to detect Cu2+, Cd2+ and PPi based on different mechanisms. The different binding mode and sensing mechanism of L with Cu2+ and Cd2+ was verified by DFT/TDDFT calculation using Gaussian 09.

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