Sensitive luminescent probes of aniline, benzaldehyde and Cr(VI) based on a zinc(II) metal-organic framework and its lanthanide(III) post-functionalizations

A novel zinc(II) metal-organic framework (MOF) {[(CH3)2NH2]2 [Zn5 (TDA)4 (TZ)4].4DMF}n (1) (H2TDA = thiophene-2,5-dicarboxylic acid and HTZ = 1H-1,2,4-Triazole) based on Zn5(COO)2 (TZ)4 pentametallic clusters and thiophene-2,5-dicarboxylic acid was synthesized and structurally characterized via the mixed-ligand strategy. This MOF exhibits a uninodal 6-connected anionic framework with pcu topology and shows solvent stability. Post-functionalization via cation exchange of 1 with Eu3+ and Tb3+ afforded two lanthanide (III) functionalized MOFs: Eu3+@1 and Tb3+@1. 1 as well as Eu3+@1 and Tb3+@1 were utilized as a highly selective and sensitive turn-off luminescent sensors for detecting aniline, benzaldehyde in DMF and Cr2O72−, CrO42− in water with low detection limits. More importantly, it is rather rare in MOF-based luminescent probes that 1 and its lanthanide (III) post-functionalized materials (Eu3+@1 and Tb3+@1) can detect aniline, benzaldehyde, Cr2O72− and CrO42−. Furthermore, the sensitivity of 1 as luminescent probes for detecting aniline and benzaldehyde could be improved via post-functionalization with Eu3+ ions.