A 2-fold interpenetrated zinc-organic framework with Lewis basic triazole sites: luminescence sensing of Fe3+ and Cr2O72-, and warm white-light emission by encapsulated Ln(3+) ions

The design and application of functional metal-organic frameworks are very important and meaningful. Herein, based on a V-shape carboxylic acid ligand, a rigid nitrogen heterocyclic ligand with a triazole group, and Zn(NO3)(2)center dot 6H(2)O, a 3D luminescent Zn-MOF [Zn-2(OBA)(2)(L-1)center dot 3DMF center dot 4H(2)O](n) (compound 1; H(2)OBA = 4,4'-oxybis(benzoic acid), L-1 = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole) with a pillared-layer structure, has been synthesized under solvothermal conditions. Two independent skeletons penetrate each other, forming a 2-fold interpenetrated structure. As an excellent chemical sensor, compound 1 can detect Fe3+ and Cr2O72- by luminescence quenching with high selectivity and sensitivity. The limits of detection of compound 1 are 0.58 mu M for Fe3+ and 1.37 mu M for Cr2O72-, respectively. Meanwhile, compound 1 can serve as a host to encapsulate Eu3+/Tb3+ ions, realizing the tunable luminescence emission of Eu3+/Tb3+-doped samples. Furthermore, the Eu3+/Tb3+-co-doped compound 1 obtained by soaking the as-synthesized MOF into Ln(3+) ion solution (total 25 mM; Eu3+ : Tb3+ = 2 : 3, molar ratio) exhibits white-light emission with ideal Commission International de I'Eclairage coordinates of (0.32, 0.33), a moderate correlated color temperature value of 6180 K, and an absolute quantum yield of 25.3%. These results indicate that compound 1 has promising applications in ion sensing and white-light emission.