Two luminescent lanthanide( III) metal- organic frameworks as chemosensors for high- efficiency recognition of Cr( VI) anions in aqueous solution plus Ji- Yong Zou, * a Ling Li, a Sheng- Yong You, a Yue- Wei Liu, a Hong- Min

Two new lanthanide(iii) metal-organic frameworks (MOFs) {[(CH3)(2)NH2](2)[Ln(4)(FDA)(7)(DMF)(2)] 0.5DMF}(n) [Ln = Eu (1), and Tb (2)] based on furan-2,5-dicarboxylic acid (H(2)FDA) have been successfully assembled and well characterized in detail. These MOFs are isostructural and demonstrate 12-connected sqc15 topologies, which are rarely observed in MOF chemistry, especially in lanthanide(iii) MOFs. Moreover, these two MOFs could show a tolerance towards moisture and organic solvents and satisfactory chemical stabilities. More importantly, they exhibit sensitive and selective luminescence quenching response towards Cr2O72- and CrO42- anions in aqueous solution with the average quenching K-sv values of 1.25 x 10(4) L mol(-1) (Cr2O72-) and 3.56 x 10(3) L mol(-1) (CrO42-) for 1 and 1.46 x 10(4) L mol(-1) (Cr2O72-) and 4.35 x 10(3) L mol(-1) (CrO42-) for 2 and the detection limits of 1.14 x 10(-4) mol L-1 (Cr2O72-) and 1.12 x 10(-4) mol L-1 (CrO42-) for 1 and 7.42 x 10(-5) mol L-1 (Cr2O72-) and 1.27 x 10(-4) mol L-1 (CrO42-) for 2. The high quenching K-sv values and low detection limits make them more feasible in sensing Cr(vi) anions in aqueous solution. The possible detection mechanism has been discussed in detail.