Separation of p‐Divinylbenzene by Selective Room‐Temperature Adsorption Inside Mg‐CUK‐1 Prepared by Aqueous Microwave Synthesis

Abstract

A new Mg(II) -based version of the porous coordination polymer CUK-1 with one-dimensional pore structure was prepared by microwave synthesis in water. Mg-CUK-1 is moisture-stable, thermally stable up to 500 °C, and shows unusual reversible soft-crystal behavior: dehydrated single crystals of the material selectively adsorb a range of organic molecules at ambient temperature and pressure. Both polar and apolar aromatic compounds, including pyridine, benzene, p-xylene, and p-divinylbenzene (p-DVB), are all readily adsorbed, while other isomers from complex mixtures of xylenes or DVBs are selectively excluded. The solvent-loaded structures have been studied by single-crystal X-ray diffraction. Time-dependent liquid sorption experiments using commercially available DVB demonstrate a high and rapid selective adsorption of p-DVB and exclusion of m-DVB and ethylvinylbenzene isomers.

Bottleneck Effect Explained by Le Bail Refinements: Structure Transformation of Mg-CUK-1 by Confining H2O Molecules

“…Mg-CUK-1 is assembled from the coordination of Mg(II) metal centers and 2,4-pyridinedicarboxylate ligand. Mg-CUK-1 crystallizes in the space group P2 1 /n and it is constructed around trinuclear [Mg 3 (µ 3 -OH)] building blocks (see Figure S1, inset) [11]. Each Mg(II) metal center shows an octahedral coordination environment and links into infinite chains of edge-and vertex-sharing Mg 3 OH triangles.…”

“…The confined H 2 O molecules are well-ordered in the pore-structure of these µ 2 -OH functionalized MOFs, working as preferential adsorption sites for the subsequent CO 2 molecules [10]. In this communication, we describe the structure transformation of Mg-CUK-1 (CUK for Cambridge University-KRICT, see SM, Figure S1) [11] due to the confined H 2 O molecules within its pores, which previously demonstrated enhanced CO 2 capture properties [12,13].…”

“…Mg-CUK-1 = [Mg 3 (OH) 2 (2,4-PDC) 2 , 2,4-PCD = 2,4-pyridinecarboxylate] was synthesized following the previously reported procedure in [11]: 2,4-Pyridinedicarboxlic acid (170 mg, 1.0 mmol) and KOH (2.0 M , 2.0 cm 3 ) in H 2 O were added to a stirred solution of Mg(NO 3 ) 2 , (380 mg, 1.5 mmol) in H 2 O (3 cm 3 ) to give a viscous, opaque, slurry mixture. The reaction mixture was placed inside a Teflon-lined Easy-Prep vessel and heated at 472 K for 35 min in a MARS microwave (CEM Corp.).…”

Methodologies for evaluation of metal–organic frameworks in separation applications

“…Fig. 28a shows that the S ads value for DynaMOF-100 (at 298 K) is about one to two orders of magnitude higher than that of MAF-X8 (at 433 K), 84 Mg-CUK-1 (at 323 K), 85 and BaX zeolite (at 393 K, and 453 K).…”

Crystals springing into action: metal–organic framework CUK-1 as a pressure-driven molecular spring

“…The channel-like CUK-1(M) composed of chains of m 3 -OH/O edge and vertex sharing metal octahedra (M ¼ Co, 19 Mg 20 ) coordinated by bidentate 2,4-pyridinedicarboxylic ligands, recently emerged as an attractive porous material owing to its promising sorption performance combined with environmentally-friendly hydrothermal synthesis and high thermal and chemical stability. [20][21][22] Its winerack topology and its relatively rigid behaviour upon guest adsorption are reminiscent to that of MIL-47(V) a MOF which interestingly underwent a hysteretic, reversible structural contraction upon exerting an external pressure of 125 MPa, 9 associated with a stored/delivered energy of 33 J g À1 . Inspired by our previous ndings on MIL-47(V), we deliberately explored the pressure-induced structural behaviour of CUK-1 in its isostructural Co and Mg forms.…”