ABSTRACT
Two new lanthanide(iii) metal-organic frameworks (MOFs) {[(CH3)2NH2]2[Ln4(FDA)7(DMF)2]·0.5DMF}n [Ln = Eu (1), and Tb (2)] based on furan-2,5-dicarboxylic acid (H2FDA) 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 Ksv values of 1.25 × 104 L mol-1 (Cr2O72-) and 3.56 × 103 L mol-1 (CrO42-) for 1 and 1.46 × 104 L mol-1 (Cr2O72-) and 4.35 × 103 L mol-1 (CrO42-) for 2 and the detection limits of 1.14 × 10-4 mol L-1 (Cr2O72-) and 1.12 × 10-4 mol L-1 (CrO42-) for 1 and 7.42 × 10-5 mol L-1 (Cr2O72-) and 1.27 × 10-4 mol L-1 (CrO42-) for 2. The high quenching Ksv 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.
ABSTRACT
Two 3D solvent-stable zinc(ii)-lanthanide(iii) heterometallic metal-organic frameworks (MOFs) {[(CH3)2NH2]2[Zn2Ln2(FDA)6(DMF)2]·2DMF}n [Ln = Eu (Zn-Eu) and Tb (Zn-Tb); H2FDA = furan-2,5-dicarboxylic acid] based on Zn2Ln2(COO)10 tetrametallic clusters and furan-2,5-dicarboxylic acid have been successfully synthesized. These MOFs can serve as luminescent sensors for the fast response and highly selective detection of aniline via luminescence quenching. More importantly, a linear correlation is observed between their luminescence and the low concentration of aniline and the detection limits of aniline are 7.5 µmol L-1 for Zn-Eu and 5.2 µmol L-1 for Zn-Tb.
