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We report that linker ligand substitution involving just one atom induces a shape‐memory effect in a flexible coordination network. Specifically, whereas SIFSIX‐23‐Cu, [Cu(SiF6)(L)2]n, (L=1,4‐bis(1‐imidazolyl)benzene, SiF62−=SIFSIX) has been previously reported to exhibit reversible switching between closed and open phases, the activated phase of SIFSIX‐23‐CuN, [Cu(SiF6)(LN)2]n (LN=2,5‐bis(1‐imidazolyl)pyridine), transformed to a kinetically stable porous phase with strong affinity for CO2. As‐synthesized SIFSIX‐23‐CuN, α, transformed to less open, γ, and closed, β, phases during activation. β did not adsorb N2 (77 K), rather it reverted to α induced by CO2 at 195, 273 and 298 K. CO2 desorption resulted in α′, a shape‐memory phase which subsequently exhibited type‐I isotherms for N2 (77 K) and CO2 as well as strong performance for separation of CO2/N2 (15/85) at 298 K and 1 bar driven by strong binding (Qst=45–51 kJ/mol) and excellent CO2/N2 selectivity (up to 700). Interestingly, α′ reverted to β after re‐solvation/desolvation. Molecular simulations and density functional theory (DFT) calculations provide insight into the properties of SIFSIX‐23‐CuN. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A 4 4 .6 10 .8 topology hybrid ultramicroporous material (HUM), {[Cu 1.5 F(SiF 6 )(L) 2.5 ]·G} n , (L = 4,4'-bisimidazolylbiphenyl, G = guest molecules), 1, formed by cross-linking interpenetrated 3D four-connected CdSO 4 -type nets with hexafluorosilicate anions is synthesized and evaluated in the context of gas sorption and separation herein. 1 is the first HUM functionalized with two different types of fluorinated sites (SiF 6 2- and F - anions) lining along the pore surface. The optimal pore size (≈5 Å) combining mixed and high-density electronegative fluorinated sites enable 1 to preferentially adsorb C 2 H 2 over CO 2 and C 2 H 4 by hydrogen bonding interactions with a high C 2 H 2 isosteric heat of adsorption (Q st ) of ≈42.3 kJ mol -1 at zero loading. The pronounced discriminatory sorption behaviors lead to excellent separation performance for C 2 H 2 /CO 2 and C 2 H 2 /C 2 H 4 that surpasses many well-known sorbents. Dynamic breakthrough experiments are conducted to confirm the practical separation capability of 1, which reveal an impressive separation factor of 6.1 for equimolar C 2 H 2 /CO 2 mixture. Furthermore, molecular simulation and density functional theory (DFT) calculations validate the strong binding of C 2 H 2 stems from the chelating fix of C 2 H 2 between SiF 6 2- anion and coordinated F - anion., (© 2024 Wiley‐VCH GmbH.)

We report that linker ligand substitution involving just one atom induces a shape-memory effect in a flexible coordination network. Specifically, whereas SIFSIX-23-Cu, [Cu(SiF 6 )(L) 2 ] n , (L=1,4-bis(1-imidazolyl)benzene, SiF 6 2- =SIFSIX) has been previously reported to exhibit reversible switching between closed and open phases, the activated phase of SIFSIX-23-Cu N , [Cu(SiF 6 )(L N ) 2 ] n (L N =2,5-bis(1-imidazolyl)pyridine), transformed to a kinetically stable porous phase with strong affinity for CO 2 . As-synthesized SIFSIX-23-Cu N , α, transformed to less open, γ, and closed, β, phases during activation. β did not adsorb N 2 (77 K), rather it reverted to α induced by CO 2 at 195, 273 and 298 K. CO 2 desorption resulted in α', a shape-memory phase which subsequently exhibited type-I isotherms for N 2 (77 K) and CO 2 as well as strong performance for separation of CO 2 /N 2 (15/85) at 298 K and 1 bar driven by strong binding (Q st =45-51 kJ/mol) and excellent CO 2 /N 2 selectivity (up to 700). Interestingly, α' reverted to β after re-solvation/desolvation. Molecular simulations and density functional theory (DFT) calculations provide insight into the properties of SIFSIX-23-Cu N ., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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 CO 2 formylation reaction. At room temperature and in the green solvent acetonitrile, CAU-10pydc could highly effectively catalyze the reaction of CO 2 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 CO 2 formylation reaction being catalyzed highly effectively by an Al-MOF under green conditions.

Coordination networks that reversibly switch between closed and open phases are of topical interest since their stepped isotherms can offer higher working capacities for gas-storage applications than the related rigid porous coordination networks. To be of practical utility, the pressures at which switching occurs, the gate-opening and gate-closing pressures, must lie between the storage and delivery pressures. Here we study the effect of linker substitution to fine-tune gate-opening and gate-closing pressure. Specifically, three variants of a previously reported pcu-topology MOF, X-pcu-5-Zn, have been prepared: X-pcu-6-Zn, 6=1,2-bis(4-pyridyl)ethane (bpe), X-pcu-7-Zn, 7=1,2-bis(4-pyridyl)acetylene (bpa), and X-pcu-8-Zn, 8=4,4'-azopyridine (apy). Each exhibited switching isotherms but at different gate-opening pressures. The N 2 , CO 2 , C 2 H 2 , and C 2 H 4 adsorption isotherms consistently indicated that the most flexible dipyridyl organic linker, 6, afforded lower gate-opening and gate-closing pressures. This simple design principle enables a rational control of the switching behavior in adsorbent materials., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)