LAUSR

Five novel 3D anionic CoIILnIII heterometallic organic frameworks (HMOFs) [(CH3)2NH2]4[Co3Ln3(OH)(TZI)6(H2O)6]·2DMA·16H2O (CoLn, Ln = Eu (1), Gd (2), Tb (3), Dy (4), Ho (5), H3TZI = 5-(4-(tetrazol-5-yl)phenyl)isophthalic acid) have been synthesized under solvothermal conditions and structurally characterized by elemental analysis, FTIR, PXRD, TGA and single-crystal X-ray diffraction. Structure analyses show that these CoLn HMOFs (1–5) are isomorphous and contain two different metal motifs: one is a triangular trinuclear Co3(μ3-OH)(μ2-tetrazolate)6 cluster, and the other is a linear trinuclear Ln3(COO)12 cluster. The adjacent CoII and LnIII clusters are connected by the TZI ligands to give a 3D heterometallic framework with a (3,3,6,10)-connected (4·6·8)(42·5)(43·53·64·85)(47·510·66·78·810·94) topology. Magnetic investigations indicated that CoDy (4) and CoHo (5) display slow magnetic relaxation behaviors under a zero dc field. The most intriguing feature is that these CoLn HMOFs (1–5) contain microporous structures with [(CH3)2NH2]+ cations being located in channels, which can successfully separate MB+ cationic dye molecules from mixed dye molecules including Rh B+, BV14+, NR0 and MO− (adsorption – take CoTb (3) as an example). At equilibrium, the removal percentage of MB+ with CoTb (3) in a mixture of dyes is about 97.5% and the mechanism of adsorption of MB+ is also explored. Such 3d–4f anionic HMOFs are unusual.