A novel imidazole-based tri-nitrogen metal cations probe with better-selectivity in ionic radius and acting as a Zn2+ fluorescence turn-on sensor

A novel imidazole-pyridine-imidazole tri-nitrogen tridentate ligand molecule Py2IM was designed and synthesized to act as a metal cations sensor, with the traditional terpyridyl sensor molecule TPyPH as reference. Unlike the TPyPH could detect six metal cations including Ag+, Zn2+, Cu2+, Ni2+, Mn2+ and Fe3+, the Py2IM with a very similar ligand architecture could only detect the three metal cations Ag+, Zn2+, and Cu2+ with the larger ionic radius. This phenomenon could be attributed to the lager cavity-size of Py2IM upon the introduction of the imidazole ring, and indicated that Py2IM possessed the better-selectivity to metal cations in ionic radius. And finally, the sensing behaviors of Py2IM on the PL spectra exhibited that the Py2IM might also be a novel Zn2+ fluorescence turn-on sensor with good sensitivity and selectivity at excitation wavelength of 365 nm. (C) 2020 Elsevier B.V. All rights reserved.