Post-Synthetic Functionalization of Ni-MOF by Eu3+ Ions: Luminescent Probe for Aspartic Acid and Magnetic Property.

Utilizing 5,5'-oxidiisophthalic acid (H4odip) ligand, one 3D framework {[Ni2(odip)(H2O)4(DMF)]·DMF·2H2O}n (1) with a rare 3-nodal (3,3,4)-connected topological net based on two types of Ni12(odip)12 and Ni24(odip)12 nanocages was prepared. To exploit the advantage of high porosity, 1 was employed as an MOF matrix, and then photoactive Eu3+ ions were introduced through a facile soaking method to get Eu3+ functionalized MOF composite Eu3+@1. Luminescent sensing experiment demonstrated that Eu3+@1 has the potential to serve as a sensitive, recyclable, and fast luminescent probe for aspartic acid, with a quenching constant of 1.565 × 103 L/mol. The result offers a new possibility for many MOF materials which are nonemissive and/or difficult to synthesize directly to realize luminescent sensing function similar to lanthanide MOFs. Moreover, 1 reveals a ferromagnetic character in the range of 6-35 K. The dynamic magnetization measurements displayed no frequency dependencies, suggesting the absence of slow magnetic relaxation.

A Multi-Functional In(III)-Organic Framework for Acetylene Separation, Carbon Dioxide Utilization, and Antibiotic Detection in Water.

The reaction of In3+ ions with 2,5-di(2H-tetrazol-5-yl) terephthalic acid (H4dtztp) affords a 3D indium-organic framework, [In(dtztp)0.5(OH)(H2O)]·H2O (1) with a (3,6)-connected net. 1 shows good thermal (300 °C) and chemical stabilities (various organic solvents and acidic/basic solutions) and excellent water tolerance (7 days at room temperature or in boiling water). The acetylene (C2H2) sorption behavior of 1 indicates significant separation selectivity over CH4, as confirmed by breakthrough experiments on the realistic gas mixtures. Meanwhile, the MOF with the Lewis and Brønsted acidic bifunctional catalytic sites catalyzes the CO2 conversion with different epoxides with high yields. The fluorescent properties reveal the efficient probing performance of 1 for nitrofurantoin (NFT) and metronidazole (MDZ) in water with a low detection limit (ppm).

Nonenzymatic Glucose Sensing and Magnetic Property Based On the Composite Formed by Encapsulating Ag Nanoparticles in Cluster-Based Co-MOF.

Utilizing the oxygen-bridged 5,5'-oxidiisophthalic acid (H4L) linker, one Co(II)-based 3D porous MOF {[Co5(L)2(OH)2(OH2)2(H2O)4]·2DMF·H2O}n (1) with pentanuclear [Co5(µ3-OH)2(µ2-OH2)2]8+ cluster was prepared. The glassy carbon electrode was modified by 1, and the obtained electrode revealed electrocatalytic performance for glucose oxidation. The porous MOF matrix is beneficial for dispersing Ag nanoparticles evenly in the interior cages or channels, so Ag@1 composite composed of both Ag nanoparticles and MOF was further prepared through deposition-reduction method to enhance electrocatalytic activity. The result demonstrates that the glucose oxidation by Ag@1 was greatly increased with low detection limit (1.32 µM) and good selectivity and sensitivity (0.135 µA µM-1), which promote the application of MOF-template porous composites as advanced electrochemical sensor materials. Furthermore, 1 shows an interesting magnetic spin-glass slow dynamics for the existing of peculiar pentanuclear Co(II) clusters.

C2H2 capture and separation in a MOF based on Ni6 trigonal-prismatic units.

A honeycomb MOF, based on rare Ni6 trigonal-prismatic supermolecular building blocks, was fabricated by utilizing an unexploited [1,1'-biphenyl]-3,3',5,5'-tetracarboxylic acid linker with -NH2 substituent groups. The MOF contains novel building blocks and an enchanting structure, and also exhibits water-stable characteristics. Uniquely, the accessible adsorption sites, arising due to the high-density Lewis-basic amino-coordinated groups and uncoordinated carboxylate O atoms in the pores, endow the MOF with excellent capture and separation capabilities for C2H2.

A Lead Carboxylate-Azolate Metal-Organic Framework Based on Hexanuclear Clusters: Luminescence and Accelerating the Thermal Decomposition of Ammonium Perchlorate.

A lead carboxylate-azolate framework, [Pb3 (µ4 -O)(L)2 (H2 O)] ⋅ 2H2 O (1), has been constructed from the reaction of 2-methyl-4-(1H-tetrazol-5-yl) benzoic acid (H2 L) and Pb(NO3 )2 under solvothermal conditions. Compound 1 contains an unprecedented hexanuclear cluster [Pb6 (µ4 -O)2 (COO)4 (CN4 )2 ], which as an 8-connected node is connected by 3-connected L linkers to give rise to a three-dimensional framework with an uncommon (3,8)-connected tfz-d; UO3 topology. Framework 1 possesses strong solid-state yellow luminescence (563 nm), which stems from ligand-to-metal charge transfer (LMCT), however, the removal of water molecules in 1 lead to the significant luminescent decrease of the sample. Importantly, in the presence of 1, the thermal decomposition of ammonium perchlorate is significantly accelerated.

Three New MOFs Induced by Organic Linker Coordination Modes: Gas Sorption, Luminescence, and Magnetic Properties.

By using a new 4,6-bis(imidazol-1-yl) isophthalic acid ligand (H2 bimip) with imidazolyl and carboxyl bifunctional groups, three new MOFs, [Co(bimip)(H2 O)0.5 ]⋅0.5 H2 O (1), [Zn(bimip)] (2), and [Mn(bimip)(H2 O)2 ]⋅H2 O (3), have been solvothermally synthesized in different solvent systems. H2 bimip displays three different coordinated modes through the imidazolyl and carboxyl groups, and different cis-cis and trans-cis configurations, which result in distinct 3D topological frameworks: a (4,8)-connected scu net for 1; a twofold interpenetrated (4,4)-connected pts net for 2; and a four-connected sra net for 3. Compounds 1 and 3 show antiferromagnetic properties, and 2 emits strong solid-state blue luminescence. Compound 1 shows good chemical stability in acidic and basic environments and in boiling water. Additionally, the polar channels in 1, which are decorated by uncoordinated carboxylate O atoms and imidazolyl fragments, allow it to adsorb CO2 molecules selectively over CH4 , and the CO2 binding sites in the framework were distinguished by molecular simulations.

Syntheses of three new isostructural lanthanide coordination polymers with tunable emission colours through bimetallic doping, and their luminescence sensing properties.

Tuning the emissive color changes of lanthanide (Ln) complexes is an important and appealing project for promoting the applications of Ln-complexes. A solvothermal reaction of 4-cyano-3-methylbenzoic acid (HL) and Ln(NO3)3·6H2O affords three isostructural Ln-complexes [Eu(L)3(H2O)2]n (1-Ln) (Ln = Eu, Gd and Tb) with one-dimensional chain structures. 1-Eu and 1-Tb show bright red and green emissions with absolute quantum yields of 3.06% and 11.96%, respectively, and the energy transfer was analyzed in detail through combined calculations. Interestingly, a series of heterometallic doped 1-TbxEu1-x coordination polymers were also obtained by mixing different ratios of Eu3+ and Tb3+ ions, which possess continuous luminescent color changes from green to yellow, orange and red. In addition, 1-Eu exhibits high quenching efficiency and low detection limit (∼10-4 M) for the simultaneous sensing of MnO4-, CrO42- and Cr2O72- ions in water.