Lock‐and‐Key and Shape‐Memory Effects in an Unconventional Synthetic Path to Magnesium Metal–Organic Frameworks

Abstract

We report an ew magnesium metal-organic framework (MOF) (CPM-107) with as pecial interaction with CO 2 . CPM-107 contains Mg 2 -acetate chains crosslinked into a3 D net by terephthalate.I th as an anionic framework encapsulating ordered extra-framework cations and solvent molecules. The desolvated form is closed and unresponsive to common gasses,s uch as N 2 ,H 2 ,a nd CH 4 .Y et, with CO 2 at 195 K, it abruptly opens and turns into ar igid porous form that is irreversible via desorption. Once opened by CO 2 ,C PM-107 remains in the stable porous state accessible to additional gas types over multiple cycles or CO 2 itself at different temperatures.T he porous phase can be re-locked to return to the initial closed phase via re-solvation and desolvation. Such peculiar properties of CPM-107 are apparently linked to aconvergence of factors related to both framework and extraframework features.T he unusual CO 2 effect is currently the only available path to porous CPM-107 which shows efficient C 2 H 2 /CO 2 separation. Metal-organicframeworks(MOFs)orporouscoordinationScheme 1. Flexible-to-rigid transformation in shape-memory metalorganic frameworks with gate opening.

A new TIFSIX anion pillared metal organic framework with abundant electronegative sites for efficient C2H2/CO2separation

“…3A, the calculated equimolar C 2 H 2 /CO 2 selectivity of ZNU-7 under 1-100 kPa is 13.0-7.7, 9.2-6.6 and 7.9-6.3 at 278, 298 and 308 K, respectively. The IAST selectivity of ZNU-7 at 298 K and 100 kPa is superior to those of many well-performing materials such as CPM-107op (5.7), 37 MUF-17 (6.01), 38 JXNU-5a (5), 39 PCM-48 (4.3), 40 iMOF-7C (4), 41 FJU-36a (2.8), 42 SNNU-63 (3.3) 43 and JNU-2 (3.5) 15b (Fig. 3D), but inferior to those of ZNU-4 (8.9), 34 Ni-Pz (10.8), 14b BSF-3 (16.3), 26 ZNU-1 (56.5) 31 and some other benchmark materials shown in Table S4.…”

A Microporous Titanate‐Based Metal‐Organic Framework for Efficient Separation of Acetylene from Carbon Dioxide

“…Since the two gas molecules have the same molecular size/shape (3.3 Å for both C 2 H 2 and CO 2 ), fine tuning of pore size or flexibility on MOFs is quite limited to achieve high separation performance. In this context, the most popular strategy is to introduce strong binding sites, such as open metal sites [25][26][27][28][29] or functional groups (e. g., NH 2 , SiF 6 2À , CN) [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] onto the pores to enforce the binding affinity for C 2 H 2 . However, there commonly exists a trade-off between selectivity and gas uptake.…”

Th-MOF showing six-fold imide-sealed pockets for middle-size-separation of propane from nature gas

“…The sharp increase after 13 kPa observed in the adsorption isotherm for butane is mainly resulted from gate opening, owning to somewhat exibility of the MOF framework. Gate opening is often encountered in MOFs and is generally used for separation [41][42][43] .…”