Experimental measurements and molecular simulations were conducted for two zeolitic imidazolate frameworks, ZIF-8 and ZIF-76. The transferability of the force field was tested by comparing molecular simulation results of gas adsorption with experimental data available in the literature for other ZIF materials (ZIF-69). Owing to the good agreement observed between simulation and experimental data, the simulation results can be used to identify preferential adsorption sites, which are located close to the organic linkers. Topological mapping of the potential-energy surfaces makes it possible to relate the preferential adsorption sites, Henry constant, and isosteric heats of adsorption at zero coverage to the nature of the host-guest interactions and the chemical nature of the organic linker. The role played by the topology of the solid and the organic linkers, instead of the metal sites, upon gas adsorption on zeolite-like metal-organic frameworks is discussed.
This study deals with the enhancement of CO 2 uptake by ligand functionalization of zeolitic imidazolate framework (ZIF) materials. The ligand dipole moment could be considered as one of the main criteria for CO 2 adsorption enhancement. To verify this hypothesis, an experimentalÀ computational study was performed on an isoreticular ZIF series with sodalite (SOD) topology using published structures (ZIF-8, ZIF-90, and ZIF-Cl) as well as hypothetical structures (ZIF-COOH and ZIF-NO 2 ) designated using DFT calculations. An analysis of structural and adsorptive properties was proposed for these materials used to separate CO 2 from CH 4 , CO, or N 2 gas. The accuracy of the calculated results was validated by comparison with our own experimental results. An exponential relationship between the ligand dipole moments and the isosteric heat of adsorption of CO 2 was highlighted. Modifying the nature of the linker (dipole moment) allows a 5-to 7-fold improvement in CO 2 selectivity for CO 2 /CH 4 , CO 2 /N 2 , and CO 2 /CO mixtures.
This study deals with the development of a soft, generic, one-pot postfunctionalization method for metal-organic frameworks (MOFs) starting from compounds with an amino group on the linker. The first step consists of transforming the amino group into azide (N(3)) by an unconventional route using tBuONO and TMSN(3). In the same vessel, the desired functionalized MOF then is obtained by the Huisgen 1,3-dipolar cycloaddition of azides to alkynes, otherwise known as the "click" reaction. The method was applied to DMOF-NH(2) and MIL-68(In)-NH(2), which represent two distinct and important classes of MOF. For both, the functionalization was complete (>90% grafting) and the crystallinity was maintained. Thanks to the large diversity and availability of cyano- and acetylene-based chemicals, this method opens the door to tailor-made functionalized MOFs.
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