A luminescent dimer as a turn-off sensor for both nitrite anion and ferric cation

The cation and anion recognition properties of a binuclear Eu(III) complex, [Eu-2((2)-(2)-H2L)(2)((2)-H2L)(2)(phen)(2)(NO3)(2)]2CH(3)OH (EuL) {H3L=2-(3-benzoylthioureido)ethanoic acid; phen=1,10-phenanthroline} have been thoroughly investigated in DMF solution at room temperature by luminescence method. These investigations revealed that the EuL dimer acts as a bifunctional turn off' sensor for both Fe3+ cation and NO2- anion. The possible luminescence quenching mechanism of Fe3+ cation and NO2- anion to the dimer has been discussed. Furthermore, the simple and portable test paper based on the EuL fluorescent sensor has been explored, which may provide a convenient method of determination of Fe3+ and NO2- ions in everyday applications.