Temperature-Dependent Supramolecular Isomeric Zn(II)-Metal–Organic Frameworks and Their Guest Exchange

Abstract

A pair of three-dimensional metal–organic framework supramolecular isomers (1a and 2a) prepared from the solvothermal reactions of Zn­(NO3)2·4H2O, 1,4-bis­(4-pyridyl)­piperazine (bpp), and 4,4′-oxybis­(benzoic acid) (H2obc) in different temperatures was structurally elucidated, and a series of guest exchanges on these isomers were performed without the loss of single crystallinity. At 110 and 130 °C in DMF/H2O, an 8-fold [4 + 4] interpenetrated coordination polymer {[Zn­(bpp)­(obc)]­·3H2O} n (1a) with sra topology and a self-penetrated coordination polymer {[Zn3(bpp)3(obc)3]­·2DMF­·4H2O} n (2a) with a new topology were isolated, respectively. In the guest-exchange experiments, water molecules in isomer 1a were displaced by acetone and ethylene glycol molecules, while dimethylformamide molecules in isomer 2a were replaced by acetone and ethylene glycol as well as bulkier diethylene glycol due to its larger void. Photoluminescence properties of two isomers and their guest-exchanged products were also measured and discussed.

Two isomeric metal–organic frameworks bearing stilbene moieties for highly volatile iodine uptake

“…For example, in the hydrothermal or solvothermal synthesis of MOFs, temperatures have an unpredictable impact on the structural prediction of the final frameworks. [51][52][53][54] But for the diffusion method, the effects of diffusion temperature are usually ignored. In this work, two novel isomeric MOFs, HSB-W8 and HSB-W9, from 1,2-bis(4′pyridylmethylamino)-ethane (hsb-2), trans-stilbene-4,4-dicarboxylate (tsbdc) and Cd(NO 3 ) 2 were prepared just by adjusting the diffusion temperature (Fig.…”

Proton-Conducting Cobalt(II) 3D MOFs Incorporating Bis(imidazole) and Polycarboxylate Linkages: Framework Topology and Interpenetration

“…The conflation of dicarboxylate and bis­(imidazole) as ancillary ligands could result in a variety of supramolecular architectures with intriguing topologies. − For example, we reported some intriguing CPs incorporating polycarboxylate ligands and 9,10-di­(1 H -imidazol-1-yl)­anthracene. , Herein, we present two new cobalt­(II) CPs based on polycarboxylate ligands and 2,6-di­(1 H -imidazol-1-yl)­pyridine (dip). − The imidazole precursor has an additional pyridine functionality. One of the carboxylate ligands is based on 4,4′-oxybis­(benzoic acid) (H 2 obb), which contains two carboxylic groups for the coordination of metals and an additional ethereal oxygen functionality. − The other polycarboxylate ligand is 1,2,4,5-benzenetetracarboxylic acid (H 4 btec), which bears four carboxylic acid moieties. − Two of the carboxylic acid groups on btec could coordinate to metal centers, whereas the uncoordinated groups could point toward channels to interact with guest molecules. Both 3D frameworks exhibit engrossing topologies and successfully manifest temperature-dependent proton conductivity with a relative humidity (RH) of 33–98%.…”

Construction of 2D Interdigitated Polyrotaxane Layers and their Transformation to a 3D Polyrotaxane by a Photocycloaddition Reaction between Wheels

“…In principle, realizing the formation of polyrotaxane-type MOFs requires a metallacycle as a wheel in which an axle threads. − So, we envisioned that the combination of an angular olefinic dicarboxylate and a bipyridyl pillar ligand may lead the formation of polyrotaxane. − ,− In this work, we employed two bis-chelating ligands, 1,4-bis­(4-pyridyl)­piperazine (bpp) − and 3,3′-stilbenedicarboxylic acid (H 2 sdc) (Figure ). Of these, the former ligand is expected to act as an axle component due to the semirigid nature, and the latter with a potent C -configuration tends to form a wheel unit via metalation.…”