Robustness, Selective Gas Separation, and Nitrobenzene Sensing on Two Isomers of Cadmium Metal–Organic Frameworks Containing Various Metal–O–Metal Chains

Abstract

Poor stability has been one of the major difficulties affecting to the practical application of metal–organic frameworks (MOFs). In this work, we obtained two 3D structurally isomeric Cd-MOFs, {[Cd6(NH2Me2)2(PTB)4(HCOO)2(H2O)]·(DMF)13·(H2O)4} n (FJU-35) and {[Cd6(NH2Me2)2(PTB)4(HCOO)2]·(DMF)6·(H2O)2} n (FJU-36) (H3PTB = pyridine-2,4,6-tribenzoic acid) containing different CdII–O–CdII chains by varying the addition agents. FJU-35 with coordinated solvent and formate in asymmetric μ3-η1:η2 coordination mode within the CdII–O–CdII chains is vulnerable to external attacks and is apt to collapse after activation, while FJU-36 with no coordinated solvent in the CdII–O–CdII chains but fully protected by the carboxylates from the ligands and the symmetric formate in the coordination mode μ3-η2:η2 is stable, and its activated sample shows efficient separation of C2H2/CH4 and C2H2/CO2 mixtures. Conversely, FJU-35 with more vulnerability is more sensitive to the detection of nitrobenzene than FJU-36.

Cage‐Like Porous Materials with Simultaneous High C2H2Storage and Excellent C2H2/CO2Separation Performance

“…To evaluate the separation performance of these materials, an ideal adsorbed solution theory (IAST) calculation was employed on the base of the single‐component C 2 H 2 and CO 2 adsorption isotherms at 298 K. As shown in the Figure 3 f, the equimolar C 2 H 2 and CO 2 adsorption selectivity of FJI‐H8‐R, series are in the range of 10.42–5.35 at 298 K, which are much higher than many other famous MOFs such as UTSA‐222(4.0) [17] UTSA‐30(3.4), [18] ZJNU‐14(3.42), [19] SNNU‐45 (8.5), [12] UPC‐112 (2.8), [20] ZJNU‐100 (3.8) [21] and FJU‐36 (2.8) [22] . Meanwhile, the C 2 H 2 adsorption of FJI‐H8‐R series at 298 K and 1 bar is much higher than most of reported MOFs.…”

Ultramicroporous Building Units as a Path to Bi‐microporous Metal–Organic Frameworks with High Acetylene Storage and Separation Performance

“…The separation factor α = q i y i /q j y j is 2.9 for an equimolar C 2 H 2 /CO 2 mixture according the breakthrough curves. This factor is larger than those of FJU‐22 (1.9), HOF‐3a (2.0), and FJU‐36 (2.1), but lower than the values of 4.4 for JCM‐1 and 10 for JXNU‐5 …”

“…Under the same temperature, adsorption selectivities of C 2 H 2 /CO 2 almost remains unchanged with the change of gas ratio (Figure d). The IAST selectivity of SNNU‐45 (8.5–4.5) at 298 K is lower than the benchmark material HOF‐3a (14), but much higher than many other famous MOFs such as UTSA‐222 (4.0), UTSA‐30 (3.4), UPC‐112 (2.8), ZJNU‐100 (3.8), and FJU‐36 (2.8) . At the same time, the C 2 H 2 adsorption amount of SNNU‐45 at 298 K and 1 atm is very high.…”

Precise Pore Space Partitions Combined with High‐Density Hydrogen‐Bonding Acceptors within Metal–Organic Frameworks for Highly Efficient Acetylene Storage and Separation

“…SNNU-27-Festill has the best selectivity among these MOFs.T he selectivity values for equimolar C 2 H 2 and CO 2 of SNNU-27-Fea tafunction of surface coverage are 5.5-2.4 (268 K), 4.0-2.3 (273 K), 4.1-1.6 (283 K), and 3.6-2.0 (298 K), respectively (Figure S44). Although the selectivity value of C 2 H 2 /CO 2 for SNNU-27-Fe at 298 Ka nd 1bar is lower than the highest IAST selectivity value of 743 (UTSA-300a), [8b] it is comparable to the reported MOFs with good separation performance,s uch as FJU-6-TATB( 3.1), [20] FJU-36a (2.8), [21] Zn-MOF-74 (2.0), [17] and UPC-200(Fe)-F-H 2 O( 2.25). [10d] Theh ighest C 2 H 2 adsorption capacity and C 2 H 2 /CO 2 selectivity of SNNU-27-Fef urther give us ah int of the potential for it in practical C 2 H 2 storage and separation.…”