Channeling carbon dioxide: The separation of gas molecules with physisorbents can be challenging because there is often a tradeoff between capacity and selectivity. Zhou et al. report a template-free hydrothermal synthesis of the one-dimensional channel zeolite mordenite, in which some silicon was replaced by iron. Rather than forming a powder that requires further shaping, this mechanically stable material self-assembled into monoliths. Iron atoms bound in tetrahedral zeolite sites narrowed the channels and enabled the size-exclusion separation of carbon dioxide (CO ₂ ) over nitrogen (N ₂ ) and methane. High CO ₂ uptake and highly efficient CO ₂ –N ₂ separation was demonstrated for both dry and humid conditions. Science , aax5776, this issue p. 315

The design of molecular sieves is vital for gas separation, but it suffers from a long-standing issue of slow adsorption kinetics due to the intrinsic contradiction between molecular sieving and diffusion within restricted nanopores. We report a molecular sieve ZU-609 with local sieving channels that feature molecular sieving gates and rapid diffusion channels. The precise cross-sectional cutoff of molecular sieving gates enables the exclusion of propane from propylene. The coexisting large channels constituted by sulfonic anions and helically arranged metal-organic architectures allow the fast adsorption kinetics of propylene, and the measured propylene diffusion coefficient in ZU-609 is one to two orders of magnitude higher than previous molecular sieves. Propylene with 99.9% purity is obtained through breakthrough experiments with a productivity of 32.2 L kg ⁻¹ .

2-Phenylimidazoline based porous hypercrosslinked ionic polymers afforded high yields in the cycloaddition of epoxides with ambient or diluted CO₂ (0.15 bar CO₂ and 0.85 bar N₂) under low or room temperature.

Porous poly(ionic liquid)s, combining the features of porous polymers and ionic moieties resembling the structures and functions of ionic liquids, have exhibited promising potential in CO₂fixationviacycloadditions with epoxides.