Systematic Ligand Modulation Enhances the Moisture Stability and Gas Sorption Characteristics of Quaternary Metal–Organic Frameworks

Abstract

Complex metal-organic frameworks (MOFs) that maintain high structural order promise sophisticated and tunable properties. Here, we build on our strategy of using combinations of structurally distinct ligands to generate a new isoreticular series of ordered quaternary Zn4O-carboxylate MOFs. Rational design of the framework components steers the system toward multicomponent MOFs and away from competing phases during synthesis. Systematic ligand modulation led to the identification of a set of frameworks with unusually high stability toward water vapor. These frameworks lose no porosity after 100 days' exposure to ambient air or 20 adsorption-desorption cycles up to 70% relative humidity. Across this series of frameworks, a counterintuitive relationship between the length of pendant alkyl groups and framework stability toward water vapor emerges. This phenomenon was probed via a series of gas and vapor adsorption experiments together with Grand Canonical Monte Carlo (GCMC) simulations, and could be rationalized on the basis of the propensity of the frameworks to adsorb water vapor and the proximity of the adsorbed water molecules to the water-sensitive metal clusters. Systematic variation of the pore volume and topography also tunes the CO2 and CH4 gas adsorption behavior. Certain of these materials display increases in their adsorption capacities of 237% (CO2) and 172% (CH4) compared to the parent framework.

Exploitation of Guest Accessible Aliphatic Amine Functionality of a Metal–Organic Framework for Selective Detection of 2,4,6-Trinitrophenol (TNP) in Water

“…2). Interestingly, Ur-MOF presented excellent hydrolytic stability as anticipated, [107][108][109][110][111][112] owing to its hydrophobic naphthalene moities (Fig. 2), which further enthused us to comprehensively investigate its selective traceamount TNP-sensing performance in water.…”

Porous Metal‐Organic Polyhedral Framework containing Cuboctahedron Cages as SBUs with High Affinity for H2 and CO2 Sorption: A Heterogeneous Catalyst for Chemical Fixation of CO2

“…The Cu II -MOF containsa highly symmetric polyhedral metal cluster (Cu 24 )w ith cuboctahedron geometry as secondary building unit (SBU). [11][12][13][14][15] However with the increasing size of the cavi-ties or pores increases the probability of interpenetration of the frameworks, which reduces the cavity size but increases the stability. Further,i ts propensity towards CO 2 sorption can be utilized for the heterogeneous catalysis of the chemical conversion of CO 2 into the corresponding cyclic carbonatesu pon reactionw ith epoxides, with high turnover number and turnover frequency values.…”

Pore‐Environment Engineering with Multiple Metal Sites in Rare‐Earth Porphyrinic Metal–Organic Frameworks

“…[1] Pioneering work has been demonstrated by Yaghi and co-workers by incorporating up to eight functional groups into multivariate MOFs (MTV-MOFs), which showed emergent properties distinct from their parent frameworks. [3] Still, this strategy only works for alimited number of MOFs,which require linkers with exactly matched sizes and symmetries.L ater on, our group intro-duced apost-synthetic method, linker installation, to engineer pore environments with precisely placed linkers in zirconium MOFs. [3] Still, this strategy only works for alimited number of MOFs,which require linkers with exactly matched sizes and symmetries.L ater on, our group intro-duced apost-synthetic method, linker installation, to engineer pore environments with precisely placed linkers in zirconium MOFs.…”