A Zeolite-Like Metal–Organic Framework Based Membrane for Reverse Selective Hydrogen Separation and Butane Isomer Sieving

Here, the fabrication of a defect-free membrane that is based on a zeolite-like metal-organic framework (ZMOF) with the underlying ana topology is reported. The unique ana -ZMOF structure provides high degree of pore connectivity, which is reflected by the fast transport of gases. Prominently, it offers an optimum pore-aperture size, affording notable sieving selectivity for butane/isobutane, and optimal pore energetics for reverse CO₂/H₂ separation. This emphasize the potential for the application of pure MOF membranes, paving the way to more sustainability of energy resources.     

Specific features of the copolymerization of acrylonitrile and acrylamide in the presence of low-molecular-mass and polymeric trithiocarbonates and properties of the obtained copolymers

Regularities of the formation of acrylonitrile-acrylamide copolymers obtained from initial monomer feeds containing 1–50 wt % acrylamide in DMSO solutions with the participation of low-molecular-mass and polymeric trithiocarbonates as reversible addition-fragmentation chain transfer agents are studied for the first time. It is shown that the copolymerization in the presence of low-molecular-mass trithiocarbonates proceeds via a pseudo-living mechanism. The synthesized copolymers prove to be inefficient as reversible addition-fragmentation chain transfer agents, a result that leads to products with bimodal molecular-mass distributions. The rheological characteristics of solutions, as well as the thermal behavior of the copolymers obtained in the absence and in the presence of reversible addition-fragmentation chain transfer agents, are studied. The effect of the synthesis conditions on the properties of the synthesized copolymers is discussed.     

Controlled synthesis of copolymers of vinyl acetate and n-butyl acrylate mediated by trithiocarbonates as reversible addition-fragmentation chain-transfer agents

The formation of copolymers of vinyl acetate and n-butyl acrylate via polymerization mediated by di-tert-butyl trithiocarbonate and dibenzyl trithiocarbonate as reversible addition-fragmentation chain-transfer agents is studied. Copolymerization mediated by low-molecular-mass reversible addition-fragmentation chain-transfer agents and by the copolymers formed in their presence proceeds via the pseudoliving mechanism. As a result, the controlled synthesis of narrowly dispersed copolymers of various compositions and desired molecular masses may be implemented. Variation in the compositions of the copolymers with conversion is investigated, and the reactivity ratios of the comonomers are found to differ significantly (r _VA = 0.01 and r _BA = 5.38). Our experimental data make it possible to infer that gradient copolymers are formed in the systems of interest in a wide range of comonomer mixture compositions.     

The structure analysis of triaryl derivatives of the group V elements: V. Spectra,crystal and molecular structure of trimesitylarsine,C27H33As

The complete X-ray structure analysis of trimesitylarsine (TMAS), C₂₇H₃₃As, has been performed. The crystals are triclinic, a 18.718, b 16.418, c 8.204 Å, α 99.99, β 97.85, γ 104.56°, Z = 4, space group P1̄ (two independent molecules in the asymmetric unit); the final value of the R-factor is 0.038. In the electronic spectrum of TMAS the long-wave band has the maximum at 276 nm which differs significantly from that of triphenylarsine (TPAS) at 249 nm. The bathochromic spectral shift and the molecular conformation are caused by the steric effects as a result of bulky methyl groups in the positions 2,4 and 6 in the phenyl rings. Two independent molecules are connected by a pseudo-axis of symmetry.