A fluorescent zinc(II) metal-organic framework for the trace of CrO42-/Cr2O72- anions generated from "one-pot" in situ synthetic approach

As one of the most attractive but challenging synthetic approaches to enrich the methodology of MOF chemistry, "one-pot" in situ synthetic approach has been attracted more and more attention due to its circumvention of the organic ligands synthesis process. Herein, we present a Zn(II)-based metal-organic framework (MOF) formulated as {[Zn(pcd)]}(n) (1) generated from the "one-pot" in situ reaction, where isonicotinic acid N'-(pyridine-4-carbonyl)-hydrazide (pcd) is formed by the hydrolysis reaction of the bent 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (bpo) ligand. 1 demonstrates a 3D 4, 4-connected cds topological structure based on Zn2N2 secondary building unit (SUB). The variation of luminescence emission towards CrO42-/Cr2O72- anions shows that 1 is a promisingly selective, sensitive and recyclable fluorescence turn-off sensor in the quantitative recognition of CrO42-/Cr2O72- anions. And the detection limit can reach as low as 5.25 mu M for CrO42- anions and 7.64 mu M for Cr2O72- anions. Moreover, the mechanism of fluorescence behavior of 1 towards CrO42-/Cr2O72- anion