A gas-selective Zn-MOF exhibits selective sensing of Fe3+ ions by doping with Tb3

Here, a new Zn2+ metal organic framework, {[Me2NH2][Zn2(L)(DTZ)]·2DMF·3H2O}n (Zn-MOF), has been synthesized with low-symmetric carboxylic acid ligand 2,6 bis(2',5'-dicarboxyphenyl)pyridine (H4L) as the main ligand and 3,5-diamino-1,2,4-riazole (DTZ) containing an electron-rich N atom as an auxiliary ligand. Because of its high structural stability and adsorption properties, it can be used to efficiently separate CO2/CH4 and C2H2/CH4. In addition, Tb@Zn-MOF was obtained by doping with Tb3+ to partially replace Zn2+. A study of its luminescence sensing performance demonstrated that Tb@Zn-MOF showed intense luminescence properties and can be used for the directional detection of Fe3+ in aqueous solution. Furthermore, PXRD analysis, UV-vis spectroscopy and X-ray photoelectron spectroscopy (XPS) were also used to study possible luminescence sensing mechanisms. The recognition mechanism for Fe3+ ions is believed to be caused by electron transfer.

Highly efficient conversion of CO2 into N-formamides catalyzed by a noble-metal-free aluminum-based MOF under mild conditions

Formamides have critical application value in the chemical industry serving as solvents or reagents for the synthesis of pharmaceuticals, agrochemicals, and dyes. Herein, we selected a green-synthesis produced aluminum-based metal-organic framework (Al-MOF) material CAU-10pydc as a catalyst to study its performance in CO2 formylation reaction. At room temperature and in the green solvent acetonitrile, CAU-10pydc could highly effectively catalyze the reaction of CO2 and N-methylaniline to N-methyl-N-phenylformamide under mild conditions. CAU-10pydc could maintain its efficient catalytic performance after five catalytic cycles, and PXRD and SEM measurements demonstrated that CAU-10pydc is stable after cyclic catalysis. The universality of this catalyst was illustrated by nine substrates with high yields. The reaction mechanism was further analyzed by DFT calculations. To our knowledge, this work is the first example of a CO2 formylation reaction being catalyzed highly effectively by an Al-MOF under green conditions.

Highly selective C2H2 and CO2 capture based on two new ZnII-MOFs and fluorescence sensing of two doped MOFs with EuIII

Two Zn(ii)-based MOFs have been constructed. The activated Zn-MOF1 and Zn-MOF2 show selective separation of C2H2 and CO2 over CH4. Eu@Zn-MOF1 and Eu@Zn-MOF2 were obtained by adding EuIII ions and showed selectivity to Fe3+ ions in aqueous solution.

Efficient Propylene/Ethylene Separation in Highly Porous Metal-Organic Frameworks

Light olefins are important raw materials in the petrochemical industry for the production of many chemical products. In the past few years, remarkable progress has been made in the synthesis of light olefins (C2-C4) from methanol or syngas. The separation of light olefins by porous materials is, therefore, an intriguing research topic. In this work, single-component ethylene (C₂H₄) and propylene (C₃H₆) gas adsorption and binary C₃H₆/C₂H₄ (1:9) gas breakthrough experiments have been performed for three highly porous isostructural metal-organic frameworks (MOFs) denoted as Fe₂M-L (M = Mn²⁺, Co²⁺, or Ni²⁺), three representative MOFs, namely ZIF-8 (also known as MAF-4), MIL-101(Cr), and HKUST-1, as well as an activated carbon (activated coconut charcoal, SUPELCO^©). Single-component gas adsorption studies reveal that Fe₂M-L, HKUST-1, and activated carbon show much higher C₃H₆ adsorption capacities than MIL-101(Cr) and ZIF-8, HKUST-1 and activated carbon have relatively high C₃H₆/C₂H₄ adsorption selectivity, and the C₂H₄ and C₃H₆ adsorption heats of Fe₂Mn-L, MIL-101(Cr), and ZIF-8 are relatively low. Binary gas breakthrough experiments indicate all the adsorbents selectively adsorb C₃H₆ from C₃H₆/C₂H₄ mixture to produce purified C₂H₄, and 842, 515, 504, 271, and 181 cm³ g^-1 C₂H₄ could be obtained for each breakthrough tests for HKUST-1, activated carbon, Fe₂Mn-L, MIL-101(Cr), and ZIF-8, respectively. It is worth noting that C₃H₆ and C₂H₄ desorption dynamics of Fe₂Mn-L are clearly faster than that of HKUST-1 or activated carbon, suggesting that Fe₂M-L are promising adsorbents for C₃H₆/C₂H₄ separation with low energy penalty in regeneration.

A Versatile Luminescent Ga-Organic Framework with Multi-Emission Centers as a Blue LED and Fluorescent Probe for Low-Temperature Detection and Selective Fe3+ Sensing

The development and utilization of 3p-block based MOFs as fluorescent materials has attracted significant attention in recent years. Herein, we have successfully constructed a versatile luminescent Ga-MOF (SNNU-63) with a 3d¹⁰ configuration and a large ligand twist configuration. Interestingly, the as-synthesized Ga-MOF exhibits excellent luminescence property and a good material for blue light-emitting diode (LED). At 80 K, this Ga-MOF shows multi-emission centers at 381, 462, and 494 nm. As a ratiometric thermometer, this Ga-MOF exhibits an excellent temperature sensing property with high relative sensitivity (S_m = 2.60 % K^-1 at 110 K). The fluorescence intensity ratio I₃₈₁/I₄₉₄ shows a very good fit for the Boltzmann results (80-240 K). Moreover, the luminescent Ga-MOF exhibits an excellent selective detection of Fe³⁺ over other metal ions in aqueous an medium, and the limit of detection (LOD) towards Fe³⁺ ions is calculated to be 1.227 × 10^-4 M. This work presents a versatile luminescent Ga-MOF material as a blue LED and fluorescent probe for low-temperature and selective Fe³⁺ sensing.

Two-dimensional rare-earth-metal coordination polymers based on biphenyl-3,3′,5,5′-tetracarboxylic acid displaying luminescence

Two coordination polymers were rationally designed and successfully constructed using the rigid multicarboxylic acid ligand biphenyl-3,3′,5,5′-tetracarboxylic acid (H4BPTC) and rare earth metal ions (Eu3+ and Ho3+) under solvothermal conditions. The compounds are poly[[tetra-μ2-acetato-bis(μ6-biphenyl-3,3′,5,5′-tetracarboxylato)tetrakis(dimethylacetamide)tetraeuropium(III)] dimethylacetamide disolvate dihydrate], {[Eu4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·2C4H9NO·2H2O} n , and poly[[tetra-μ2-acetato-bis(μ6-biphenyl-3,3′,5,5′-tetracarboxylato)tetrakis(dimethylacetamide)tetraholmium(III)] pentahydrate], {[Ho4(C16H6O8)2(C2H3O2)4(C4H9NO)4]·5H2O} n , Single-crystal X-ray diffraction analysis reveals that both polymers possess a two-dimensional structure and they also display good thermal stability up to ca 280 °C and photoluminescence with an orange–red light emission.

Controllable Synthesis of Centrosymmetric/Noncentrosymmetric Phases for the Family of Halogen-Based Photonic Coordination Polymers to Enhance the Phase-Matching Second-Harmonic-Generation Response

The nonlinear-optical (NLO) materials with second-harmonic-generation (SHG) response need to crystallize in the noncentrosymmetric space group. It is very difficult to control the synthetic conditions to solely form a noncentrosymmetric phase for the materials with noncentrosymmetric and centrosymmetric conformations. Herein, we found that the temperature and halogen anion play an important role during the formation procedure of the pure noncentrosymmetric or centrosymmetric phase for the halogen-based family of coordination polymers to yield hybrid materials with a phase-matching SHG response as well as inherit the primary excellent photonic property of organic linkers. Our results provide a good choice for the design and construction of novel materials with a particular photonic property.

Micropore Regulation in Ultrastable [Sc3O]-Organic Frameworks for Acetylene Storage and Purification

High storage capacity, high separation selectivity, and high structure stability are essential for an idea gas adsorbent. However, it is not easy to achieve all three at the same time, even for the promising metal-organic framework (MOF) adsorbents. We demonstrate herein that robust [Sc₃O]-organic frameworks could be regulated by a micropore combination strategy for high-performance acetylene adsorption. Under the same solvent system with formic acid as a modulator, similar tritopic ligands extend [Sc₃O(COO)₆] trigonal-prismatic clusters to generate SNNU-5-Sc and SNNU-150-Sc adsorbents. Notably, the two Sc-MOFs can keep their architectures over 24 h in water at different pH values (2-12) or at 90 °C. Modulated by the linker symmetry, the final stacking metal-organic polyhedral cages produce open window sizes of about 10 Å for SNNU-5-Sc and 5 Å + 7 Å for SNNU-150-Sc. Due to such micropore combinations, SNNU-5-Sc exhibits a top-level C₂H₂ uptake of 211.2 cm³ g^-1 (1 atm and 273 K) and SNNU-150-Sc shows high C₂H₂/CH₄, C₂H₂/C₂H₄, and C₂H₂/CO₂ selectivities of 80.65, 4.03, and 8.19, respectively, under ambient conditions. Dynamic breakthrough curves obtained on a fixed-bed column and grand canonical Monte Carlo (GCMC) simulations further support their prominent acetylene storage and purification performance. High framework stability, storage capacity, and separation selectivity make SNNU-5-Sc and SNNU-150-Sc ideal acetylene adsorbents in practical applications.

Enhanced Sieving of C2-Hydrocarbon from Methane by Fluoro-Functionalization of In-MOF with Robust Stability

Developing efficient adsorbent materials is crucial for adsorption and separation to realize the purification of energy source and raw chemicals. Here, we report a novel and robust 3D In-based MOF built up with fluorine-functionalized ligands, QMOF-2F, with improved separation properties of C2-light hydrocarbons over methane at room temperature respect isoreticular non-fluorinated MOF. QMOF-2F shows a remarkable chemical stability in different solvents, including water, and pH (2-12). DFT calculations support the key role of fluorine-functionalization on the improved performance of QMOF-2F.

The anionic Zn-MOF composed of 1D columnar SBUs for highly C2H2/CH4 selective adsorption, dye adsorption and fluorescence sensing

An anionic three-dimensional framework {(Me2NH2)2[Zn8(L)6(ad)4(μ4-O)]·10DMF·11H2O}(Zn-MOF, L2-=4,4'-(3-aminopyridine-2,5-diyl)dibenzoic acid, ad-=adeninate) with a column-layered structure was synthesized. Structural studies show that the Zn-MOF has octahedral cages [Zn8(ad)4(μ4-O)], adjacent cages are connected by O...

A new boron cluster anion pillared metal organic framework with ligand inclusion and its selective acetylene capture properties

A novel microporous boron cluster pillared metal–organic framework BSF-10 was synthesized with ligand inclusion for efficient C2H2/CO2 and C2H2/C2H4 adsorption separation.

A novel luminescent phosphor of a metal–organic framework with orange-red emission

A novel metal–organic framework (compound 1) was rationally designed and successfully constructed using carboxylic acid and pyridine derivatives as bilinkers, possessing good photoluminescence properties with orange-red emission.

An unusual F-bridged dual-trinuclear Mg–organic framework as a luminescent thermometer for highly efficient low-temperature detection

A novel Mg-MOF with unusual μ3-F dual-trinuclear cluster was successfully afforded by utilizing a solvent system of DMA/DMPU/HFP. Interestingly, as a luminescent thermometer, this MOF exhibits excellent low-temperature sensing capabilities.

A pyridyl-decorated Zr-organic framework for enhanced gas separation and CO2 transformation

A Zr-based MOF with UiO-66 topology, which was defined as Py-UiO-66, has been synthesized by modifying the ligand of p-phthalic acid with a pyridine group. Py-UiO-66 possesses excellent chemical stability in aqueous solutions of pH = 0-13, especially when the pore structure is functionalized by hanging bare Lewis basic pyridine groups. Results of gas adsorption experiment show that Py-UiO-66 has the ability to selectively absorb C₂H₂ and CO₂ rather than CH₄. More importantly, Py-UiO-66 has an efficient catalytic effect in CO₂ cycloaddition.

Cobalt-Based Metal-Organic Frameworks for Adsorption of CO2 and C2 Hydrocarbons: Effect of Auxiliary Ligands with Different Functional Groups

Recently, metal-organic frameworks (MOFs) have been investigated as potential materials for CO₂ capture and light hydrocarbon storage/separation due to their high porosity, large surface area, and tunable skeleton structures. In this work, the six cobalt-based MOFs 1-6 were successfully synthesized under solvothermal conditions by a mixed-ligand strategy. 1 and 2 have the same framework structure with a topology of {4²·5}₂{4⁴·5¹⁰·6⁷·7⁶·8}, while the structures of the 3-6 frameworks are the same with a topology of {4²·5}₂{4⁴·5¹⁰·6⁹·7⁴·8}. The adsorption properties of these MOFs for CO₂ and C₂ hydrocarbons were then investigated, and the effect of the functional groups was discussed. The results revealed that the introduction of amino and bromo groups could effectively strengthen the adsorption performance.

Tuning the Pore Surface of an Ultramicroporous Framework for Enhanced Methane and Acetylene Purification Performance

Both methane (CH₄) and acetylene (C₂H₂) are important energy source and raw chemicals in many industrial processes. The development of an energy-efficient and environmentally friendly separation and purification strategy for CH₄ and C₂H₂ is necessary. Ultramicroporous metal-organic framework (MOF) materials have shown great success in the separation and purification of small-molecule gases. Herein, the synergy effect of tritopic polytetrazolate and ditopic terephthalate ligands successfully generates a series of isoreticular ultramicroporous cadmium tetrazolate-carboxylate MOF materials (SNNU-13-16) with excellent CH₄ and C₂H₂ purification performance. Except for the uncoordinated tetrazolate N atoms serving as Lewis base sites, the pore size and pore surface of MOFs are systematically engineered by regulating dicarboxylic acid ligands varying from OH-BDC (SNNU-13) to Br-BDC (SNNU-14) to NH₂-BDC (SNNU-15) to 1,4-NDC (SNNU-16). Benefiting from the ultramicroporous character (3.8-5.9 Å), rich Lewis base N sites, and tunable pore environments, all of these ultramicroporous MOFs exhibit a prominent separation capacity for carbon dioxide (CO₂) or C2 hydrocarbons from CH₄ and C₂H₂. Remarkably, SNNU-16 built by 1,4-NDC shows the highest ideal adsorbed solution theory CO₂/CH₄, ethylene (C₂H₄)/CH₄, and C₂H₂/CH₄ separation selectivity values, which are higher than those of most famous MOFs with or without open metal sites. Dynamic breakthrough experiments show that SNNU-16 can also efficiently separate the C₂H₂/CO₂ mixtures with a gas flow rate of 4 mL min^-1 under 1 bar and 298 K. The breakthrough time (18 min g^-1) surpasses most best-gas-separation MOFs and nearly all other metal azolate-carboxylate MOF materials under the same conditions. The above prominently CH₄ and C₂H₂ purification abilities of SNNU-13-16 materials were further confirmed by the Grand Canonical Monte Carlo (GCMC) simulations.

Design of a heterometallic Zn/Ca-MOF decorated with alkoxy groups on the pore surface exhibiting high fluorescence sensing performance for Fe3+ and Cr2O72−

Reported herein is a heterometallic Zn/Ca-MOF decorated with alkoxy groups on the pore surface exhibiting high fluorescence sensing performance for Fe³⁺ and Cr₂O₇²⁻.

A new honeycomb metal–carboxylate-tetrazolate framework with multiple functions for CO2 conversion and selective capture of C2H2, CO2 and benzene

A stable Cd-MOF was built by a carboxylate-tetrazolate ligand, which contains hexagonal channels and reveals multiple functions including separation of CO₂/CH₄, C₂H₂/CO₂, C₂H₂/CH₄ and benzene/cyclohexane, and catalytic conversion of CO₂ with epoxides.