Multifunctional Zn–Ln (Ln = Eu and Tb) heterometallic metal–organic frameworks with highly efficient I2 capture, dye adsorption, luminescence sensing and white-light emission

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 50; no. 33; pp. 11619 - 11630
• Main Authors: Gao, Wei, Han, Wei, Cui-Li, Wang, Jie-Ping Liu, Zhang, Xiu-Mei
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.09.2021
• Subjects: Adsorption; Crystallography; Cyclohexane; Dyes; Ligands; Light emission; Luminescence; Luminescence quenching; Metal-organic frameworks; Pollutants; Selectivity; Terbium; Topology; White light; Zinc
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/d1dt01968f

A new family of isostructural 3d–4f heterometallic metal–organic frameworks (HMOFs), [Zn3EuxTb2−x(TZI)4(DMA)5(H2O)3]·4DMA [x = 0 (1), 0.3 (2), 0.6 (3), 0.9 (4), 1 (5), 1.2 (6), 1.5 (7), 1.8 (8), 2 (9)], has been synthesized using the 5-(4-(tetrazol-5-yl) phenyl)isophthalic acid (H3TZI) ligand, LnIII ions and ZnII ions under solvothermal conditions. All HMOFs exhibit a (3,3,4,5,5)-connected 63·63(42·62·82)(4·65·8)(4·66·83) topology, which features three different types of motifs: one is a mononuclear ZnII ion and the other two motifs are binuclear [Zn(COO)3Ln] clusters. The adsorption experiments indicate that Zn3Tb2 (1) could efficiently remove almost all I2 from cyclohexane solution after 12 h and also showed better adsorption towards neutral red (NR) dye (adsorption: only the Zn3Tb2 (1) was taken as one representative). Simultaneously, the luminescence sensing showed that Zn3Tb2 (1) and Zn3Eu2 (9) have excellent response and sensitivity towards pollutants such as Fe3+ ions and 2,4,6-trinitrophenol (TNP) with high selectivity and a fairly low limit of detection through luminescence quenching effect. Moreover, seven trimetallic-doped HMOFs 2–8 analogues of Zn3Ln2 (single) HMOFs were designed and prepared, showing different changes of luminescent color. More interestingly, Zn3Eu1.5Tb0.5 (7) with white-light emission was fabricated by doping relative concentrations of Eu3+ and Tb3+ ions. To the best of our knowledge, Zn3Eu1.5Tb0.5 (7) represents a novel kind of heterometallic Zn3Ln2 HMOFs with white-light emission. It could be deduced that the excellent characteristics, namely strong typical luminescence emission of ZnII and LnIII ions, microporous channels, active open metal sites (tetra-coordinated ZnII–metal sites), and uncoordinated carboxylate O atoms and uncoordinated tetrazolate N atoms, made the above HMOFs an ideal platform for adsorption, luminescence sensing, and white-light emission. More significantly, these HMOFs are the first reported Zn–Ln heterometallic materials with the H3TZI ligand.