Two Cd(Ⅱ)/Mn(Ⅱ) complexes based on multinuclear metal clusters for Fe(Ⅲ) and Cr(Ⅵ) fluorescence detection and magnetic properties

Abstract

Two novel complexes, {[Cd3(L)2(H2O)2]·(H2O)4}n (1) and {[Mn(HL)(H2O)2]·(H2O)}n (2), which are synthesized by the reaction of 3-(2, 4-dicarboxyphenyl)-4-carboxypyridine ligand with cadmium and manganese metal ions under the solvothermal method. The complex 1 is a 3D framework based upon trinuclear [Cd3(μ2-COO)4(μ1-COO)4(N)2] SBUs, and the complex 2 is a one-dimensional metal oxygen chain based upon binuclear [Mn2(μ2-COO)2(μ1-COO)2(N)2] SBUs. The solid fluorescence analysis of complex 1 reveals that the emission peak of 451 nm when its excitation peak is 336 nm. The fluorescence detection experiments of complex 1 showed that Fe3+, Cr2O72− and CrO42− can effectively to be detected. Furthermore, their limits of detection are 1.47 × 10−3 M, 1.31 × 10−3 M and 1.25 × 10−3 M, respectively. It has good recovery properties as a potential multifunctional fluorescence sensor. Besides, the quenching mechanism of fluorescence sensing is also discussed. In addition, the magnetic studies of complex 2 show strong antiferromagnetic interactions between its neighboring Mn(II) ions.