Microwave-Assisted Synthesis of Defects Metal-Imidazolate-Amide-Imidate Frameworks and Improved CO₂ Capture

In this work, we report three isostructural 3D frameworks, named <b>IFP-11</b> (R = Cl), <b>IFP-12</b> (R = Br), and <b>IFP-13</b> (R = Et) (IFP = Imidazolate Framework Potsdam) based on a cobalt­(II) center and the chelating linker 2-substituted imidazolate-4-amide-5-imidate. These chelating ligands were generated <i>in situ</i> by partial hydrolysis of 2-substituted 4,5-dicyanoimidazoles under microwave (MW)-assisted conditions in DMF. Structure determination of these IFPs was investigated by IR spectroscopy and a combination of powder X-ray diffraction (PXRD) with structure modeling. The structural models were initially built up from the single-crystal X-ray structure determination of <b>IFP-5</b> (a cobalt center and 2-methylimidazolate-4-amide-5-imidate linker based framework) and were optimized by using density functional theory calculations. Substitution on position 2 of the linker (R = Cl, Br, and Et) in the isostructural <b>IFP-11</b>, <b>-12</b>, and <b>-13</b> allowed variation of the potential pore window in 1D hexagonal channels (3.8 to 1.7 Å). The potential of the materials to undergo specific interactions with CO₂ was measured by the isosteric heat of adsorption. Further, we resynthesized zinc based IFPs, namely <b>IFP-1</b> (R = Me), <b>IFP-2</b> (R = Cl), <b>IFP-3</b> (R = Br), and <b>IFP-4</b> (R = Et), and cobalt based <b>IFP-5</b> under MW-assisted conditions with higher yield. The transition from a nucleation phase to the pure crystalline material of <b>IFP-1</b> in MW-assisted synthesis depends on reaction time. <b>IFP-1</b>, <b>-3</b>, and <b>-5</b>, which are synthesized by MW-assisted conditions, showed an enhancement of N₂ and CO₂, compared to the analogous conventional electrical (CE) heating method based materials due to crystal defects

Experimental and Theoretical Analysis of the Influence of Different Linker Molecules in Imidazolate Frameworks Potsdam (IFP-n) on the Separation of Olefin–Paraffin Mixtures

Four metal–organic frameworks with similar topology but different chemical environment inside the pore structure, namely, IFP-1, IFP-3, IFP-5, and IFP-7, have been investigated with respect to the separation potential for olefin–paraffin mixtures as well as the influence of the different linkers on adsorption properties using experiments and Monte Carlo simulations. All IFP structures show a higher adsorption of ethane compared to ethene with the exception of IFP-7 which shows no selectivity in breakthrough experiments. For propane/propane separation, all adsorbents show a higher adsorption for the olefin. The experimental results agree quite well with the simulated values except for the IFP-7, which is presumably due to the flexibility of the structure. Moreover, the experimental and simulated isotherms were confirmed with breakthrough experiments that render IFP-1, IFP-3, and IFP-5 as suitable for the purification of ethene from ethane