A highly sensitive and selective chemosensors for detection of Zn2+ and its application in live cell imaging

A novel salen derivative, named as 6,6′-((1E,1′E)-(1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))bis(4-(4-iodobutyl)-2-methylphenol) (PA), was obtained for the detection of Zn 2+ . PA exhibited highly sensitive and selective via a chelation mechanism, which was promoted by Zn 2+ , accompanied by enhanced fluorescence. After adding various metal ions in the PA solution, only Zn 2+ caused PA fluorescence enhancement. Other cations (such as Ag + , Al 3+ , Ba 2+ , Ca 2+ , Cd 2+ , Cr 3+ , Cu 2+ , Fe 3+ , Hg 2+ , K + , La 3+ , Li + , Mg 2+ , Na + , Ni 2+ and Pb 2+ ) cannot induce similar response. The binding stoichiometry and detection limit was 1:1 and 16.3 nM, respectively, which is superior to the reported Zn 2+ fluorescent probes based on salen derivatives. The binding process was reasonably speculated by fluorescence measurements, infrared spectroscopy, 1 H NMR titrations, FT-IR, mass spectroscopy (MS) and density functional theory (DFT) calculation. In addition, PA can be used for Zn 2+ fluorescence imaging in HeLa cells. This work indicated that this probe would be of great application prospect in medical diagnosis.