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A bifunctional thiourea‐amine‐based organocatalyst (Takemoto's catalyst), employing a metal‐free approach, is presented for the regioselective ring‐opening polymerization (ROP) of optically active (D and L) methyl glycolide (MG). In this study, a chiral version of Takemoto's catalyst efficiently promotes the ROP of MG at room temperature, yielding poly(lactic‐co‐glycolic acids) (PLGAs) with predicted molecular weights and narrow polydispersity indices (PDI≤1.2). These PLGAs exhibit highly alternating structures without transesterification, as confirmed by 1H NMR, SEC, and MALDI‐TOF analyses. Additionally, various macromolecular architectures, including linear and star‐shaped PLGAs, were successfully synthesized using the corresponding multi‐functional alcohol initiators while maintaining the same alternating structures and regioselectivity with PLGA obtained from benzyl alcohol as initiator. Computational studies were conducted to elucidate the mechanism of alternating PLGA formation, revealing two key transition states (TSs): TS‐1, which implicates the nucleophilic attack of the hydroxyl group of the initiator or propagating chain on the carbonyl carbon of MG, and TS‐2, which involves the subsequent ring‐opening of the cyclic ester. The results indicate that ring‐opening occurs at both the glycolyl and lactyl sites, with a preference for the glycolyl site, as supported by experimental results. The resulting atactic PLGAs are amorphous, rendering them suitable for drug delivery applications. [ABSTRACT FROM AUTHOR]

Although methane poses environmental concerns, it is employed in hydrogen production processes such as steam‐methane reforming (SMR), which has an issue of by‐products released. Initiatives are being pursued to address CO and CO2 emissions using carbon capture methods, with the goal of minimizing environmental harm while improving pure hydrogen generation from syngas. In this study, porous coordination network (PCN‐250) has been studied for its selective adsorption property towards CO, CO2 and H2O as syngas mixture to obtain pure hydrogen. For this purpose, the trimetallic cluster node Fe2M (where Fe2 represents the 3+ oxidation state and M is Cr(II), Mn(II), Fe(II), Co(II), Ni(II), and Zn(II)) has been considered. Fe(III) in combination with metal atoms like Cr(II), Co(II), or Ni(II) has been found to exhibit enhanced adsorption properties towards CO, CO2 and H2O. The molecule with the strongest interaction was found to be H2O over Fe(III)2Zn(II) cluster and weakest interaction was found between H2 and Fe(III)2Ni(II). Charge transfer, natural bond orbital (NBO) and spin density analyses reveal the electronic structural properties of this combination, leading to enhanced adsorption of CO and CO2. [ABSTRACT FROM AUTHOR]

A Ni-based pyrazolate MOF (NiBDP) is studied for SO2 adsorption under static conditions, demonstrating a high SO2 uptake of 8.48 mmol g-1 at 298 K and 1 bar while maintaining a high chemical stability. The influence of Ni(II) coordinatively unsaturated metal sites and coordinated water on the SO2 adsorption performance of this MOF is investigated by using a combination of experimental techniques, including FTIR and in situ DRIFTS measurements, along with Density Functional Theory calculations. The porefilling of the SO2 adsorbates within the material, at the molecular level, is further unravelled through grand Canonical Monte Carlo simulations employing a newly DFT-derived accurate set of force field parameters. [ABSTRACT FROM AUTHOR]

Two tetracarboxylic linkers containing seven‐membered rings are synthesized and utilized in metal–organic framework (MOF) syntheses, leading to the two new compounds DUT‐184 and DUT‐193. The introduced odd angles between carboxylates in a new dihydro‐azepine‐containing linker lead to exotic Zn‐based MOFs: a 3D structure based on two catenated sets of 2D nets in DUT‐184 and a cubic structure with so far unknown topology in the DUT‐193 framework. The mesoporous DUT‐193 shows high porosity upon adsorption of N2, Ar, CH4, and CO2 at their standard boiling points. Grand canonical Monte Carlo simulations show good agreement between experimental and theoretical results and shine light on the microscopic adsorption mechanism at low pressure. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have attracted much attention for the effective capture of contaminants from air. Herein, density functional theory (DFT) calculations and grand canonical Monte Carlo (GCMC) simulations were combined to systematically assess the adsorption performance of the cagelike UiO-66 nanoporous MOF functionalized by metal-(II) catecholate [CatM-(II), where M-(II) = Mg-(II), Mn-(II), Fe-(II), Co-(II), Ni-(II), Cu-(II), Zn-(II), Pd-(II), and Pt-(II)] with respect to NOx potentially present at very low concentration (from the ppm to ppb levels). The adsorption modes and energetics of NOx toward metal-(II) catecholate functions were first examined systematically using cluster DFT calculations in order to determine the optimum metal-(II) for effective NOx capture. The best CatFe-(II) was further incorporated in the crystal structure of UiO-66 and force-field parameters to accurately describe the specific interactions between Fe-(II), and both NOx were derived from periodic DFT calculations and further implemented in a GCMC scheme to predict the adsorption isotherms in a whole range of gas pressure. These calculations revealed that UiO-66-CatFe-(II) exhibits steep-adsorption isotherms for both NOx, leading to excellent adsorption uptake at very low gas pressure (from 10–9–10–4 bar). This finding complements the portfolio of nanoporous materials that has so far been almost exclusively tested in operation conditions at much higher NOx concentration (>1000 ppm). [ABSTRACT FROM AUTHOR]

In this study, new metal organic frameworks have been designed by modifying the linker of IRMOF-1 with different carbon flakes (circular, rectangular and rhombus). The adsorption of gas molecules such as H2, CH4 and CO2 has been investigated at different temperatures and pressures using Grand Canonical Monte Carlo (GCMC) simulation. It is interesting to observe from the results that the modification of the IRMOF-1 linker with carbon flakes enhances the gas storage capacity. It is possible to note that IRMOF-1 modified with circular carbon flakes is highly suitable for CO2 storage. On the other hand, IRMOF-1 with a rhombus linker has considerable potential for H2 molecule storage. These findings form a solid foundation for designing aesthetically pleasing as well as functional new metal organic framework molecules for gas storage applications. [ABSTRACT FROM AUTHOR]