Two unique 2D metal-organic frameworks based on various metal-oxygen chains for high sensitivity sensing of Fe(III) and Cr(VI) in aqueous media

Two new 2D MOFs, namely, {[Cd2(HL)(H2O)(DMF)2]center dot(H2O)center dot(DMF)}n (1), {[Co2(HL)(H2O)(DMF)2]center dot(H2O)center dot (DMF)}n (2) were constructed under the solvothermal conditions by using 2,4-di(2 ',5 '-dicarboxylphenyl)benzoic acid and d10 metal ion Cd(II) and Co(II). Because the diversity of ligands leads to two different coordination patterns in complexes 1-2, resulting in 1 and 2 with multiple structures. Both 1 and 2 exhibit a 3D supramo-lecular framework, which based on different metal-oxygen chains. The chains form a 2D layered structure through the carboxyl oxygen atoms in the ligand. The solid-state luminescence spectra of 1 at room temperature showed that the maximum emission peak is 458 nm (lambda ex = 346 nm). At the same time, 1 showed high fluo-rescence selectivity and low detection limit for Fe3+ cations, Cr2O72-and CrO42-anions in aqueous solution, and can be used as a potential multifunctional material for the detection of these substances. In addition, the fluo-rescence sensing properties and quenching mechanism of the above ions are discussed in detail.