A Sensitive Probe for the Detection of Zn(II) by Time-Resolved Fluorescence

A new, highly sensitive fluorescent sensor for Zn(II) ion (a tris(2-pyridylmethyl)amine derivative) shows very strong binding and Zn(II) concentration-dependent biexponential time-resolved fluorescence (TRF) decay profiles that can be used for ratiometric estimates of Zn(II) concentrations. The ligand−metal complexes were characterized in solution by spectroscopic techniques and in the solid state by X-ray crystallography. The TRF studies revealed that the sensor aggregates in the absence of Zn(II) in a ligand concentration-dependent manner, a complication that is discerned by TRF but not by steady-state fluorescence ratiometric sensing techniques. It is shown that the same TRF methods are highly useful for monitoring Zn(II) concentrations in A549 epithelial lung cells in vitro and that the results were consistent with those in solution.