Increasing the stability of Mg₂(dobpdc) metal–organic framework in air through solvent removal

Abstract

A simple way to increase MOFs stability in air? Solvent removal. Counterintuitive? No, it is not. The condensation of water is delayed by removing all the solvent (polar) molecules from the pores.

Effect of Pore Size, Solvation, and Defectivity on the Perturbation of Adsorbates in MOFs: The Paradigmatic Mg2(dobpdc) Case Study

“…The cell parameters calculated with the inclusion of the D* terms are closer to their experimental values (a = b = 21.7008(8) Å and c = 6.847 (1) Å). 5 The differences with respect to the calculated values 0.5/0.9% and 0.8/2% with and without the correction (see Section S2 of the SI). For the gas complexes, a loading of 1 gas molecule per Mg 2+ was considered by maintaining the P3221 symmetry.…”

“…This result is in agreement with previous works on this topic. 3,5 Besides the reversibility of the adsorption process, solvent polarity influenced also the time evolution of the adsorption process. In fact, for toluene and dichlorometane (that is for the solvents having the lowest polarity) the time evolution of the IR spectra after each vapor dosage was characterized by a parallel increase of the intensity of all the solvent bands until equilibration was reached.…”

“…Nevertheless, systematic studies on solvated or defective materials are rare. [3][4][5] We have adopted this material as a paradigmatic case for the study of the effect of pore size, availability of open metal sites and structural defectivity on the sorptive properties of MOFs, with the aim of enabling the design of better sorbents and better tools for their characterization. Mg2(dopbdc) (H4-dobpdc = 4,4'-dihydroxy-(1,1'-biphenyl)-3,3'-dicarboxylic acid) is a metal organic framework whose structure results from parallel MgO5 rows arranged in an hexagonal "honeycomb" structure.…”

“…Spectroscopic studies on gas adsorption in MOFs are rarely dealing with not activated 4 or damaged materials. 5 Nevertheless, such studies would represent a useful benchmark to easily identify the effectiveness of activation protocols and the materials' robustness to handling and activation. They would also be useful for evaluating the impact of poisoning and damaging on the way the material perturbs an adsorbate.…”

Design and Characterization of MOF s (Metal–Organic Frameworks) for Innovative Applications

“…Nevertheless, this was not expected, being the adsorption enthalpy of the magnesium ion sufficient to guarantee an high affinity toward CO2 at low coverage in these conditions. In this latter study, a significant low activation temperature was adopted (87) (120°C (69) versus and 250°C (88)) that it is known to be not able to free all the Mg 2+ from the solvent for both Mg2(dobdc) (88) and Mg2(dobpdc) (89). In this study, the material was not checked after the activation by, for example IR.…”