Thiophene-Functionalized Cadmium(II)-Based Metal-Organic Frameworks for CO2 Adsorption with Gate-Opening Effect, Separation, and Catalytic Conversion.

Two new porous three-dimensional cadmium(II) metal-organic frameworks (MOFs) containing thiophene-appended carboxylate acid ligands, formulated as [Cd(L1)(4,4'-Bipy)]n.2n(DMF) (1) and [Cd(L2)(4,4'-Bipy)]n.2n(DMF) (2) [where L1 = 5-{(thiophen-2-ylmethyl)amino}isophthalate, L2 = 5-{(thiophen-3-ylmethyl)amino}isophthalate, 4,4'-Bipy = 4,4'-bipyridine, and DMF = N,N'-dimethylformamide] have been synthesized and structurally characterized. The gas adsorption analysis of the activated MOFs shows that they specifically capture CO2 (uptake amount 4.36 mmol/g under 1 bar at 195 K) over N2 and CH4. Moreover, both MOFs show a gate-opening-closing phenomenon, which features the S-shaped isotherms with impressive hysteretic desorption during the CO2 adsorption-desorption process at 195 K. Ideal adsorbed solution theory (IAST) calculations of these MOFs displayed that the obtained selectivity values for CO2/CH4 (50:50) and CO2/N2 (15:85) are approximately 8.6-23 and 93-565, respectively. Configurational bias Monte Carlo simulation was performed to understand the mechanism behind the better CO2 adsorption by these MOFs. Catalytic activity of the MOFs for the CO2 fixation reactions with different epoxides to form cyclic carbonates were tested. These MOFs demonstrated a significantly high conversion (94-99%) of epichlorohydrin to the corresponding cyclic carbonate within 8 h of reaction time at 1 bar of CO2 pressure, at 70 °C, and they can be reused up to five cycles without losing considerably their activity.

Crystal structure and Hirshfeld surface analysis of 3,3'-[ethane-1,2-diylbis(-oxy)]bis-(5,5-di-methyl-cyclo-hex-2-en-1-one) including an unknown solvate.

The title mol-ecule, C18H26O4, consists of two symmetrical halves related by the inversion centre at the mid-point of the central -C-C- bond. The hexene ring adopts an envelope conformation. In the crystal, the mol-ecules are connected into dimers by C-H⋯O hydrogen bonds with R 2 2(8) ring motifs, forming zigzag ribbons along the b-axis direction. According to a Hirshfeld surface analysis, H⋯H (68.2%) and O⋯H/H⋯O (25.9%) inter-actions are the most significant contributors to the crystal packing. The contribution of some disordered solvent to the scattering was removed using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. The solvent contribution was not included in the reported mol-ecular weight and density.

Crystal structure and Hirshfeld surface analysis of (Z)-4-({[2-(benzo[b]thio-phen-3-yl)cyclo-pent-1-en-1-yl]meth-yl}(phen-yl)amino)-4-oxobut-2-enoic acid.

In the title compound, C24H21NO3S, the cyclopentene ring adopts an envelope conformation. In the crystal, mol-ecules are linked by C-H⋯π inter-actions, forming ribbons along the a axis. Inter-molecular C-H⋯O hydrogen bonds connect these ribbons to each other, forming layers parallel to the (01) plane. The mol-ecular packing is strengthened by van der Waals inter-actions between the layers. The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 46.0%, C⋯H/H⋯C 21.1%, O⋯H/H⋯O 20.6% and S⋯H/H⋯S 9.0%.

Crystal structure and Hirshfeld surface analysis of (Z)-4-oxo-4-{phen-yl[(thio-phen-2-yl)meth-yl]amino}-but-2-enoic acid.

In the title compound, C15H13NO3S, the mol-ecular conformation is stable with the intra-molecular O-H⋯O hydrogen bond forming a S(7) ring motif. In the crystal, mol-ecules are connected by C-H⋯O hydrogen bonds, forming C(8) chains running along the a-axis direction. Cohesion of the packing is provided by weak van der Waals inter-actions between the chains. A Hirshfeld surface analysis was undertaken to investigate and qu-antify the inter-molecular inter-actions. The thio-phene ring is disordered in a 0.9466 (17):0.0534 (17) ratio over two positions rotated by 180°.

Crystal structure and Hirshfeld surface analysis of 1-[6-bromo-2-(4-fluoro-phen-yl)-1,2,3,4-tetra-hydroquinolin-4-yl]pyrrolidin-2-one.

In the title compound, C19H18BrFN2O, the pyrrolidine ring adopts an envelope conformation. In the crystal, mol-ecules are linked by inter-molecular N-H⋯O, C-H⋯O, C-H⋯F and C-H⋯Br hydrogen bonds, forming a three-dimensional network. In addition, C-H⋯π inter-actions connect mol-ecules into ribbons along the b-axis direction, consolidating the mol-ecular packing. The inter-molecular inter-actions in the crystal structure were qu-anti-fied and analysed using Hirshfeld surface analysis.

Crystal structure and Hirshfeld surface analysis of 8-benzyl-1-[(4-methyl-phen-yl)sulfon-yl]-2,7,8,9-tetra-hydro-1H-3,6:10,13-diep-oxy-1,8-benzodi-aza-cyclo-penta-decine ethanol hemisolvate.

The asymmetric unit of the title compound, 2C31H28N2O4S·C2H6O, contains a parent mol-ecule and a half mol-ecule of ethanol solvent. The main compound stabilizes its mol-ecular conformation by forming a ring with an R 1 2(7) motif with the ethanol solvent mol-ecule. In the crystal, mol-ecules are connected by C-H⋯O and O-H⋯O hydrogen bonds, forming a three-dimensional network. In addition, C-H⋯π inter-actions also strengthen the mol-ecular packing.