Colorimetric fluorescence of the 1,10-phenantholineyl-imidazole sensor probe for the selective detection of Zn2+ and Cd2+ ions

A colorimetric fluorescent probe, 4-(1H-imidazolo[4,5-f][1,10]phenanthroline-2-yl)-N, N-diphenylaniline (PIN), was designed, synthesized and characterized for the sensitive and selective detection of Zn 2+ and Cd 2+ . The color of the solution changed from blue to yellow visible to the naked eye with the addition of Zn 2+ and Cd 2+ . The probe PIN showed good anti-interference to Zn 2+ and Cd 2+ in the presence of a variety of metal ions, and the fluorescence intensity showed a good linear relationship with the concentrations of Zn 2+ and Cd 2+ , with detection limits of 34.84 nM and 35.76 nM, respectively. The probe PIN complexed 2:1 with Zn 2+ and Cd 2+ , and the complexation constants were 1.03 × 10 4 M −1 (PIN − Zn 2+ , R 2  = 0.9971) and 1.50 × 10 4 M −1 (PIN − Cd 2+ , R 2  = 0.9981), respectively. In addition, the PIN could be recovered by EDTA and could be effectively monitored for Zn 2+ and Cd 2+ at pH 4–11, with good results in actual water samples. The HepG-2 cells maintained over 95 % of viability after 24 h exposure to PIN, which identified the extremely low toxic of PIN and could be used for in vivo cell imaging.