Metal-organic frameworks (MOFs) are thought to be a set of promising hydrogen storage materials; however, little is known about the interactions between hydrogen molecules and pore walls as well as the diffusivities of hydrogen in MOFs. In this work, we performed a systematic molecular simulation study on the adsorption and diffusion of hydrogen in MOFs to provide insight into molecular-level details of the underlying mechanisms. This work shows that metal-oxygen clusters are preferential adsorption sites for hydrogen in MOFs, and the effect of the organic linkers becomes evident with increasing pressure. The hydrogen storage capacity of MOFs is similar to carbon nanotubes, which is higher than zeolites. Diffusion of hydrogen in MOFs is an activated process that is similar to diffusion in zeolites. The information derived in this work is useful to guide the future rational design and synthesis of tailored MOF materials with improved hydrogen adsorption capability.

Fine-tuning of effective pore size of microporous materials is necessary to achieve precise molecular sieving properties. Herein, we demonstrate that room temperature ionic liquids can be used as cavity occupants for modification of the microenvironment of MOF nanocages. Targeting CO2 capture applications, we tailored the effective cage size of ZIF-8 to be between CO2 and N2 by confining an imidazolium-based ionic liquid [bmim][Tf2 N] into ZIF-8's SOD cages by in-situ ionothermal synthesis. Mixed matrix membranes derived from ionic liquid-modified ZIF-8 exhibited remarkable combinations of permeability and selectivity that transcend the upper bound of polymer membranes for CO2 /N2 and CO2 /CH4 separation. We observed an unusual response of the membranes to varying pressure, that is, an increase in the CO2 /CH4 separation factor with pressure, which is highly desirable for practical applications in natural gas upgrading.

Herein, we report that a new flexible coordination network, NiL (L=4-(4-pyridyl)-biphenyl-4-carboxylic acid), with diamondoid topology switches between non-porous (closed) and several porous (open) phases at specific CO and CH pressures. These phases are manifested by multi-step low-pressure isotherms for CO or a single-step high-pressure isotherm for CH . The potential methane working capacity of NiL approaches that of compressed natural gas but at much lower pressures. The guest-induced phase transitions of NiL were studied by single-crystal XRD, in situ variable pressure powder XRD, synchrotron powder XRD, pressure-gradient differential scanning calorimetry (P-DSC), and molecular modeling. The detailed structural information provides insight into the extreme flexibility of NiL . Specifically, the extended linker ligand, L, undergoes ligand contortion and interactions between interpenetrated networks or sorbate-sorbent interactions enable the observed switching.

Porous materials capable of selectively capturing CO 2 from flue-gases or natural gas are of interest in terms of rising atmospheric CO 2 levels and methane purification. Sizeexclusive sieving of CO 2 over CH 4 and N 2 has rarely been achieved. Herein we show that acrystal engineering approach to tuning of pore-size in ac oordination network, [Cu(quinoline-5-carboxyate) 2 ] n (Qc-5-Cu)ena+bles ultra-high selectivity for CO 2 over N 2 (S CN % 40 000) and CH 4 (S CM % 3300). Qc-5-Cu-sql-b,anarrowpore polymorph of the square lattice (sql) coordination network Qc-5-Cu-sql-a, adsorbs CO 2 while excluding both CH 4 and N 2 .E xperimental measurements and molecular modeling validate and explain the performance. Qc-5-Cu-sql-b is stable to moisture and its separation performance is unaffected by humidity.

The capacity of NH3 in PIL [Bim][NTf2] was up to 2.69 mol NH3 per mol IL under ambient conditions.