Oxalamide-Functionalized Metal Organic Frameworks for CO₂ Adsorption

Abstract

Metal–organic frameworks (MOFs) have received great attention in recent years as potential adsorbents for CO2 capture due to their unique properties. However, the high cost and their tedious synthesis procedures impede their industrial application. A series of new CO2-philic oxalamide-functionalized MOFs have been solvothermally synthesized: {[Zn3(μ8-OATA)1.5(H2O)2(DMF)]·5/2H2O·5DMF} n (Zn-OATA), {[NH2(CH3)2]­[Cd­(μ4-HOATA)]·H2O·DMF} n (Cd-OATA), and {[Co2(μ7-OATA)­(H2O)­(DMF)2]·2H2O·3DMF} n (Co-OATA) (H4OATA = N,N′-bis­(3,5-dicarboxyphenyl)­oxalamide). In Zn-OATA, the [Zn2(CO2)4] SBUs are connected by OATA4– ligands into a 3D framework with 4-connected NbO topology. In Cd-OATA, two anionic frameworks with a dia topology interpenetrated each other to form a porous structure. In Co-OATA, [Co2(CO2)4] units are linked by four OATA4– to form a 3D framework with binodal 4,4-connected 42·84 PtS-type topology. Very interestingly, Cu-OATA can be prepared from Zn-OATA by a facile metal ions exchange procedure without damaging the structure while the CO2 adsorption ability can be largely enhanced when Zn­(II) metal ions are exchanged to Cu­(II). These new MOFs possess channels decorated by the CO2-philic oxalamide groups and accessible open metal sites, suitable for highly selective CO2 adsorption. Cu-OATA exhibits a significant CO2 adsorption capacity of 25.35 wt % (138.85 cm3/g) at 273 K and 9.84 wt % (50.08 cm3/g) at 298 K under 1 bar with isosteric heat of adsorption (Q st) of about 25 kJ/mol. Cu-OATA presents a very high selectivity of 5.5 for CO2/CH4 and 43.8 for CO2/N2 separation at 0.1 bar, 298 K. Cd-OATA exhibits a CO2 sorption isotherm with hysteresis that can be originated from structural rearrangements. Cd-OATA adsorbs CO2 up to 11.90 wt % (60.58 cm3/g) at 273 K and 2.26 wt % (11.40 cm3/g) at 298 K under 1 bar. Moreover, these new MOFs exhibit high stability in various organic solvents, water, and acidic or basic media. The present work opens a new opportunity in the development of improved and cost-effective MOF adsorbents for highly efficient CO2 capture.

Coordination Unsaturation and Basic Site-Immobilized Nanochannel in a Chemorobust MOF for 3-Fold-Increased High-Temperature Selectivity and Fixation of CO2 under Mild Conditions with Nanomolar Recognition of Roxarsone

“…As shown in Figure , the uptake amounts for CO 2 are 59.2, 41.8, and 30.2 cm 3 /g at 273, 298, and 313 K, respectively; which are comparable to some of the recently functionalized MOFs (Figure a and Table S3). ,− The above uptake capacities are found to be in good agreement with the simulated CO 2 sorption amounts (Figure S17), calculated using the Grand canonical Monte Carlo (GCMC) simulation via the RASPA program package . Surmising the hydrolytic stability of the MOF together with the importance of CO 2 capture under humid conditions, we studied CO 2 adsorption of the water-treated sample.…”

A stable 2D luminescent metal–organic framework as a highly sensitive sensor for Fe3+and Cr2O72−/CrO42−in water

“…The H 4 BDPO ligand was synthesized according to a previous method. 16 Other reagents were directly purchased and used without further treatment. Elemental analysis was carried out on a PerkinElmer 2400-II CHNS/O analyser.…”

“…In this contribution, the N , N ′-bis(3,5-dicarboxyphenyl)oxalamide (H 4 BDPO) ligand containing four carboxylate groups and two functional amide groups has been selected to construct high-dimensional luminescent MOFs for the following advantages: 16 i) H 4 BDPO is a multidentate ligand possessing four carboxyl groups and two back-to-back amides, which means that it has many more possible coordination modes and prefers to coordinate with more metal ions to construct high-dimensional structures. In particular, the special orientation of two isophthalate modules is conducive to acquire intriguing porous architectures.…”

“…Nevertheless, very few efforts have been dedicated to the coordination chemistry of the H 4 BDPO ligand. 16 In addition, the d 10 electronic configuration of Cd 2+ ions and π-conjugated ligands are usually used to explore luminescent materials.…”

Computational Simulation of CO2/CH4 Separation on a Three-Dimensional Cd-Based Metal–Organic Framework

“…They evaluated the capacity and selectivity of these MOFs for CO 2 /CH 4 and CO 2 /N 2 mixtures and conducted simulations to determine the uptake of individual gases (CO 2 , CH 4 , and N 2 ) using the Grand Canonical Monte Carlo (GCMC) method. Cu-OATA [H 4 OATA: N,N′-bis(3,5dicarboxyphenyl)-oxalamide)] demonstrated a high degree of selectivity of 5.5 for CO 2 /CH 4 separation at 0.1 bar and 298 K. 86 In another study, the GCMC simulation technique offered an in-depth comprehension of the methoxy group functionalization process required to attain a balance between gas uptake and selectivity in a series of rigid Mg-MOFs. 87 89 The researchers conducted a thorough characterization of Zr-oxide-MOFs in terms of their ability to adsorb CO 2 , utilizing highthroughput GCMC simulations.…”