Weidong Fan

Expanded Porous Metal-Organic Frameworks by SCSC: Organic Building Units Modifying and Enhanced Gas-Adsorption Properties.

Two amino-functional copper metal-organic frameworks of formula [Cu3(ATTCA)2(H2O)3]·2DMF·11H2O·12EtOH (1) (H3ATTCA = 2-amino-[1,1:3,1-terphenyl]-4,4,5-tricarboxylic acid, pyz = pyrazine, DMF = dimethylformamide) and [Cu3(ATTCA)2(pyz)(H2O)]·2DMF·12H2O·8EtOH (2) were synthesized under solvothermal conditions and characterized by single-crystal X-ray diffraction, infrared spectroscopy, elemental analyses, thermogravimetric analyses, and powder X-ray diffraction. Single-crystal X-ray diffraction analysis revealed that both complexes 1 and 2 are built of the Cu2(COO)4 paddlewheel secondary building units with an fmj topology. Importantly, complex 1 can be transformed into complex 2 by the single-crystal to single-crystal transformation of which the coordinated water molecules are replaced with pyz molecules. However, the adsorption abilities of 2 are obviously lower than those of 1, as its pores are partially blocked by pyz molecules. Moreover, gas-adsorption analysis showed that the amino-functional 1 possesses higher gas-adsorption capacity than UMCM-151 for N2, H2, CH4, and C2H2, especially for CO2.

A Stable Amino-Functionalized Interpenetrated Metal–Organic Framework Exhibiting Gas Selectivity and Pore-Size-Dependent Catalytic Performance

An amino-functionalized doubly interpenetrated microporous zinc metal-organic framework (UPC-30) has been solvothermally synthesized. UPC-30 can be stable at 190 °C and confirmed by powder X-ray diffraction. Gas adsorption measurements indicate that UPC-30 exhibits high H2 adsorption heat and CO2/CH4 separation efficiency. After the exchange of Me2NH2+ by Li+ in the channels, the H2 adsorption heat increased by 19.7%. Because of the existence of -NH2 groups in the channels, UPC-30 can effectively catalyze Knoevenagel condensation reactions with high yield and pore-size-dependent selectivity.

Enhancing light hydrocarbon storage and separation through introducing Lewis basic nitrogen sites within a carboxylate-decorated copper–organic framework

A novel nanoporous Cu metal–organic framework (NEM-4) with open CuII sites, Lewis basic nitrogen sites, and uncoordinated –COO− groups exhibits both outstanding uptake capacities (in cm3 (STP) g−1) for C2H2 (204), C2H4 (164.1), C2H6 (172.2), C3H6 (197.4), and C3H8 (196.1) and high selectivities for C2H2/CH4 (63.2), C3H6/CH4 (174.8), and C3H8/CH4 (168.3) under ambient conditions. After eight cycles of adsorption–desorption tests, only 8.2% and 10.3% decrease in the acetylene and propene storage capacities was observed, indicating an excellent repeatability. Compared with 1 (carboxylate decorated NOTT-101), when nitrogen sites are inserted, the C2–C3 hydrocarbon uptakes of NEM-4 can be significantly enhanced. Grand Canonical Monte Carlo and first-principles calculations reveal that not only the open CuII sites but also the uncoordinated –COO− groups and the nitrogen sites play significant roles in its high C2–C3 hydrocarbon uptakes. Moreover, the adsorption and separation of cationic dyes in NEM-4 are highly size and charge state dependent, and the adsorbed methylene blue (MB+) in NEM-4 can be efficiently released in an NaCl-containing CH3OH solution. This study reveals that the combination of open metal sites, carboxylate groups, Lewis basic pyridyl sites, and appropriate pore geometry is responsible for the high adsorption/separation of light hydrocarbons in NEM-4.

A MOF-derived coral-like NiSe@NC nanohybrid: an efficient electrocatalyst for the hydrogen evolution reaction at all pH values

A coral-like NiSe@NC nanohybrid as an effective electrocatalyst for the hydrogen evolution reaction (HER) at all pH values, constructed via the in situ selenation of a Ni-MOFs precursor, is reported. The electrocatalyst shows overpotentials of 123 mV, 250 mV and 300 mV in 0.5 M H2SO4, 1.0 M KOH and 1.0 M PBS, respectively, to afford a current density of 10 mA cm-2. Meanwhile, NiSe@NC also exhibits a small Tafel slope and superior long-term stability over a wide pH range. The excellent electrocatalytic performance should be ascribed to the unique coral-like structure with a large BET specific surface area (125.4 m2 g-1) and mesoporous features, as well as synergistic effects between NiSe nanocrystals and highly conductive N-doped porous carbon.

A fluorine-functionalized microporous In-MOF with high physicochemical stability for light hydrocarbon storage and separation

The storage and separation of hydrocarbons is of great importance for the petrochemical industry. Herein, we report a fluorine-functionalized microporous indium (In) metal–organic framework (UPC-104) for light hydrocarbon storage and separation. UPC-104 can be stable up to 300 °C, and can retain its framework in acidic and alkaline aqueous solutions (pH 1–11). Remarkably, the material exhibits very high H2 (230.8 cm3 g−1, 2.06 wt% at 77 K and 1 bar), C2H2 (187.0 cm3 g−1 at 273 K and 1 bar), and C3H6/C3H8 adsorption capacity (276.5 cm3 g−1 and 250.4 cm3 g−1 for C3H6 and C3H8 at 273 K and 1 bar), and shows potential for the separation of light hydrocarbons (C2H2, C2H4, C2H6, C3H6, C3H8, n-C4H10, and i-C4H10 relative to CH4), as shown by single component gas sorption and selectivity calculations.

Solvent-induced framework-interpenetration isomers of Cu MOFs for efficient light hydrocarbon separation

By tuning interpenetrated and non-interpenetrated frameworks, a pair of Cu-paddlewheel framework-interpenetration isomers (UPC-34, [Cu3(L)2(H2O)3]·2DMF·3EtOH·3H2O and UPC-35, [Cu3(L)2(H2O)3]·2DMF·2Diox·3H2O) based on a tripodal ligand (H3L = 4,4′-((5-carboxy-1,3-phenylene)bis(ethyne-2,1-diyl))dibenzoic acid) has been synthesized and characterized. The interpenetrated framework (UPC-35) is more stable than the non-interpenetrated one (UPC-34). Due to the 2-fold interpenetration, UPC-35 has a pore size distribution of ∼4.5 A, which is close to the kinetic diameters of light hydrocarbons (C1–C3), and thus exhibits high gas-uptake capacities for C3H6 and C3H8. Furthermore, UPC-35 is an effective adsorbent for the selective separation of C3/C2/C1 light hydrocarbons.