A "turn-on" lanthanide complex chemosensor for recognition of lead(II) based on the formation of nanoparticles

A functional amide-type pincer ligand was designed and synthesized, which could effectively capture Tb3+ ions to form a phosphorescence complex-based chemosensor Tb-1. The chemosensor could further coordinate with Pb2+ ions and display a turn-on phosphorescence response. This sensing process was analyzed in detail by steady-state luminescence spectroscopy, time-resolved luminescence spectroscopy, electron microscopy and dynamic tight scattering, which suggest that the formation of Pb2+-induced hydroxide nanoclusters can adjust the optical signal of the external luminescence compound by embedment and fixation of Tb3+ complexes. Furthermore, Tb-1 could effectively eliminate the signal interference from the short-lived fluorescence and improve the signal-to-noise ratio to increase the accuracy of the detection for Pb2+. An understanding of the recognition mechanism of the Tb3+ complex-based chemosensor and the application of the characteristic spectra of lanthanide ions might be able to provide more opportunities to develop highly selective optical chemosensors.