Separation of Xylene Isomers through Selective Inclusion: 1D → 2D, 1D → 3D, and 2D → 3D Assembled Coordination Polymers via β‑Sheets

The separation of xylene isomers has been achieved through sequential and selective crystallization of coordination polymers of Cu­(II) with flexible bis­(pyridylcarboxamide) ligand (<b>L</b>). The order of preference for inclusion induced crystallization was shown to be <i>o</i>-xylene > <i>m</i>-xylene > <i>p</i>-xylene. Although all three xylenes included CPs having distinct differences in terms of their crystal structures, they all have exhibited a tendency to assemble via β-sheet hydrogen bonds to form 3D architectures containing channels. The preferential inclusion of isomers of xylenes was confirmed by single crystal X-ray, ¹H NMR, and GC. The bulk purity of xylenes was also confirmed by XRPD patterns

Metallogels and Silver Nanoparticles Generated from a Series of Transition Metal-Based Coordination Polymers Derived from a New Bis-pyridyl-bis-amide Ligand and Various Carboxylates

A new series of coordination polymers, namely, <b>CP2</b> [{(H₂O)­Co_1.5(μ-3-bpna)_1.5(μ-btc)}·3DMF·3H₂O]_α, <b>CP3</b> [{Cd­(μ-3-bpna)­(μ-hbtc)}·CH₃OH·2H₂O]_α, <b>CP4</b> [{Co­(μ-3-bpna)­(μ-ipa)}·DMF·2H₂O]_α, <b>CP5</b> [{Co­(μ-3-bpna)­(μ-1,3-pda)}·DMF]_α, <b>CP6</b> [Cd­(μ-3-bpna)_0.5(μ-1,3-pda)]_α, <b>CP7</b> [(H₂O)­Co_0.5(μ-3-bpna)_0.5(μ-1,4-pda)_0.5]_α, and <b>CP8</b> [{Zn­(μ-3-bpna)­(μ-oba)}·DMF·2H₂O]_α, has been synthesized by reacting a hydrogen-bond-functionalized bis-pyridyl ligand, namely, <i>N</i>′,<i>N</i>″-di­(pyridin-3-yl)­naphthalene-2,6-dicarboxamide, with various transition metal salts and different di- or tricarboxylates (as co-ligand) displaying 2D and 3D network topology and having lattice-occluded solvents in the majority of cases. A 1D coordination polymer, namely, <b>CP1</b> [{Ag_0.5(μ-3-bpna)}_0.5·0.5BF₄·CH₃CN]_α, has also been isolated by reacting 3-<b>bpna</b> with AgBF₄ in the absence of any carboxylate co-ligand. All of the CPs were characterized by single crystal X-ray diffraction. Interestingly, two such CPs, namely, <b>CP1</b> and <b>CP2</b>, produced metallogels, which were characterized by rheology, transmission electron microscopy, and X-ray powder diffraction. The metallogel of <b>CP1</b> produced Ag nanoparticles within the gel bed upon exposure to light

Metallogels and Silver Nanoparticles Generated from a Series of Transition Metal-Based Coordination Polymers Derived from a New Bis-pyridyl-bis-amide Ligand and Various Carboxylates

A new series of coordination polymers, namely, <b>CP2</b> [{(H₂O)­Co_1.5(μ-3-bpna)_1.5(μ-btc)}·3DMF·3H₂O]_α, <b>CP3</b> [{Cd­(μ-3-bpna)­(μ-hbtc)}·CH₃OH·2H₂O]_α, <b>CP4</b> [{Co­(μ-3-bpna)­(μ-ipa)}·DMF·2H₂O]_α, <b>CP5</b> [{Co­(μ-3-bpna)­(μ-1,3-pda)}·DMF]_α, <b>CP6</b> [Cd­(μ-3-bpna)_0.5(μ-1,3-pda)]_α, <b>CP7</b> [(H₂O)­Co_0.5(μ-3-bpna)_0.5(μ-1,4-pda)_0.5]_α, and <b>CP8</b> [{Zn­(μ-3-bpna)­(μ-oba)}·DMF·2H₂O]_α, has been synthesized by reacting a hydrogen-bond-functionalized bis-pyridyl ligand, namely, <i>N</i>′,<i>N</i>″-di­(pyridin-3-yl)­naphthalene-2,6-dicarboxamide, with various transition metal salts and different di- or tricarboxylates (as co-ligand) displaying 2D and 3D network topology and having lattice-occluded solvents in the majority of cases. A 1D coordination polymer, namely, <b>CP1</b> [{Ag_0.5(μ-3-bpna)}_0.5·0.5BF₄·CH₃CN]_α, has also been isolated by reacting 3-<b>bpna</b> with AgBF₄ in the absence of any carboxylate co-ligand. All of the CPs were characterized by single crystal X-ray diffraction. Interestingly, two such CPs, namely, <b>CP1</b> and <b>CP2</b>, produced metallogels, which were characterized by rheology, transmission electron microscopy, and X-ray powder diffraction. The metallogel of <b>CP1</b> produced Ag nanoparticles within the gel bed upon exposure to light

Two-Dimensional Coordination Polymers with “X”-Shaped Cavities as Adsorbents of Oxoanion Pollutants and Toxic Dyes

The role of cationic and neutral two-dimensional (2D) coordination polymers (CPs) in the efficient capture of inorganic pollutants (chromate and dichromate) and toxic dyes has been explored. Two cationic CPs with Ag­(I) salts of BF₄^– and ClO₄^– anions and one neutral CP with Cd­(NO₃)₂ of bis­(pyridylcarboxamide) ligands have been structurally characterized, and it was found that all of them have isostructural 2D CPs. The sorption of chromate/dichromate by CPs via anion exchange mechanism was shown to depend not only on the nature of the network but also on the nature of the anion present in the as-synthesized host. Among three CPs, the BF₄^– containing Ag­(I) CP exhibited a better ability of sorbing chromate and dichromate from very dilute solution of sorbates (10^–4 M). On the other hand, neutral Cd­(II) CP containing NO₃^– ion were found to have a better ability to sorb chromate/dichromate from somewhat concentrated (10^–1 M) solutions. Further, BF₄^– and NO₃^– containing CPs exhibit selective sorption of chromate from the solution containing mixture of CrO₄^2–, NO₃^–, SO₄^2–, and BF₄^– in equimolar concentrations. The structure of chromate sorbed material was determined with the help of the as-synthesized Cd­(II) CP of chromate. Further, Ag­(I) CP containing BF₄^– ion and Cd­(II) CP containing NO₃^– ion have shown the ability for selective dye sorption and luminescence based detection of dichromate ions, respectively

Adsorption of Natural Gas in Metal–Organic Frameworks: Selectivity, Cyclability, and Comparison to Methane Adsorption

Evaluation of metal–organic frameworks (MOFs) for adsorbed natural gas (ANG) technology employs pure methane as a surrogate for natural gas (NG). This approximation is problematic, as it ignores the impact of other heavier hydrocarbons present in NG, such as ethane and propane, which generally have more favorable adsorption interactions with MOFs compared to methane. Herein, using quantitative Raman spectroscopic analysis and Monte Carlo calculations, we demonstrate the adsorption selectivity of high-performing MOFs, such as MOF-5, MOF-177, and SNU-70, for a methane and ethane mixture (95:5) that mimics the composition of NG. The impact of selectivity on the storage and deliverable capacities of these adsorbents during successive cycles of adsorption and desorption, simulating the filling and emptying of an ANG tank, is also demonstrated. The study reveals a gradual reduction in the storage performance of MOFs, particularly with smaller pore volumes, due to ethane accumulation over long-term cycling, until a steady state is reached with substantially degraded storage performance