A highly selective turn on fluorescence sensor for Hg2+ based on rhodamine derivative

A novel fluorescent rhodamine based chemosensor (E)-3',6'-bis(diethylamino)-2-((2-(pyridin-2-ylmethoxy)benzylidene)amino)spiro[isoindoline-1,9'-xanthen]-3-one, RSP, had been successfully developed and well characterized by NMR, FT-IR and Mass spectroscopy. The chemosensor exhibits high selectivity for Hg(2+) over other ions (Ag(+), Pb(2+), Cu(2+), Ni(2+), Fe(3+), Co(2+), Zn(2+) and Cd(2+)) with fluorescence enhancement in ethanol solution. More over the detection limit of the sensor is in the 10(-6) M level. The binding ratio of RSP-Hg(2+) complex was determined to be 1:1 according to the Job plot. Test strips based on RSP were fabricated, which showed the application of the sensor for detection of mercuric ions in water by naked eyes.