A pyrrole-containing hydrazone and its Cu2+ complex: an easily accessible optical chemosensor system for the successive detection of Zn2+/Cu2+ and pyrophosphate

Abstract

A simple chemosensor, namely, ethyl 5-(isonicotinoylimino)methyl-2,4-dimethyl-pyrrole-3-carboxylate (1), was synthesized and characterized. Probe 1 exhibited great selectivity when used as an off–on fluorescent sensor for Zn²⁺. Moreover, 1 can be used as a colorimetric probe for the detection of Cu²⁺ in semiaqueous media. The putative binding mechanism of 1 with its target analytes was confirmed through UV-Vis absorption analysis, fluorescence measurements, mass spectroscopy, ¹H NMR analysis, and density functional theory calculations. In addition, the resulting 1 + Cu²⁺ complex can be used as a colorimetric sensor for pyrophosphate. Probe 1 is successfully applied in monitoring intracellular Zn²⁺ in the glioma cell line U251.