A Schiff-based sensor with turn-on fluorescence for selective detection of Hg2+

A simple Schiff-base colorimetric receptor 1 was prepared. It exhibits an 'off-on-type' mode with high sensitivity in the presence of Hg2+. The change in color is very easily observed by the naked eye in the presence of Hg2+, whereas other metal cations do not induce such a change. A Job plot indicated a 1:1 complexation stoichiometry between receptor 1 and Hg2+. The association constant for 1-Hg2+ in Tetrahydrofuran (THF) was determined to be 1.3 × 109 M-1 using a Hill plot.