Isolation of CO 2 from acetylene (C 2 H 2 )v ia CO 2selective sorbents is an energy-efficient technology for C 2 H 2 purification, but as trategic challenge due to their similar physicochemical properties.T here is still no specific methodology for constructing sorbents that preferentially trap CO 2 over C 2 H 2 .W ereport an effective strategy to construct optimal pore chemistry in aC e IV -based ultramicroporous metalorganic framework Ce IV -MIL-140-4F,based on charge-transfer effects,f or efficient inverse CO 2 /C 2 H 2 separation. The ligandto-metal cluster charge transfer is facilitated by Ce IV with lowlying unoccupied 4f orbitals and electron-withdrawing Fatoms functionalizedt etrafluoroterephthalate,a ffording ap erfect pore environment to matchCO 2 .The exceptional CO 2 uptake (151.7 cm 3 cm À3 )along with remarkable separation selectivities (above4 0) set an ew benchmark for inverse CO 2 /C 2 H 2 separation, which is verified via simulated and experimental breakthrough experiments.The unique CO 2 recognition mechanism is further unveiled by in situ powder X-ray diffraction experiments,F ourier-transform infrared spectroscopym easurements,and molecular calculations.

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Isoreticular functionalization is a well‐elucidated strategy for pore environment tuning and the basis of gas separation performance in extended frameworks. The extension of this approach to discrete porous molecules such as metal‐organic cages (MOCs) is conceptually straightforward but hindered by synthetic complications, especially stability concerns. We report the successful isoreticular functionalization of a zirconium MOC with tetrazole moiety by bottom‐up synthesis. The title compound (ZrT‐1‐tetrazol) shows promising C2H2/CO2 and C2H2/C2H4 separation performance, as demonstrated by adsorption isotherms, breakthrough experiments, and density functional theory calculations. The design analogy between MOFs and highly stable MOCs may guide the synthesis of novel porous materials for challenging separation applications.

Adsorptive separation is an energy‐efficient technology for the separation of C2 hydrocarbons. However, it remains a critical problem to directly produce high‐purity C2H4 from ternary C2H2/C2H4/C2H6 mixtures by simultaneously trapping C2H2 and C2H6. Herein, we report the one‐step C2H4 purification from the ternary mixture by a metal–organic framework Zn(ad)(int) (ad=adeninate; int=isonicotinate). The material combines dense heterocyclic rings and accessible uncoordinated O atoms as strong binding sites for C2H6 and C2H2. Its spindle‐like cage exhibits an interesting shape matching with the targeted molecules, affording Zn(ad)(int) not only high separation selectivity for C2H6/C2H4 and C2H2/C2H4, but also excellent gas capacity. Breakthrough experiments show that polymer‐grade C2H4 can be separated from the ternary mixtures with a record productivity of 1.43 mmol g−1. In situ powder X‐ray diffraction and Fourier transform infrared spectrum analyses further provide deep insights into the separation mechanism.

Two-dimensional covalent organic frameworks (2D COFs) have been widely viewed as rigid porous materials with smooth and reversible gas sorption isotherms. In the present study, we report an unusual hysteresis step in the CO2 adsorption isotherm of a 2D COF, TAPB-OMeTA. In situ powder X-ray diffraction (PXRD) measurements, computational modeling, and Pawley refinement indicate that TAPB-OMeTA experiences slight interlayer shifting during the CO2 adsorption process, resulting in a new structure that is similar but not identical to the AA stacking structure, namely, a quasi-AA stacking structure. This interlayer shifting is responsible for the step in its CO2 adsorption isotherm. We attribute the interlayer shifting to the interactions between COF and CO2, which weaken the attraction strength between adjacent COF layers. Notably, the repulsion force between the methoxy groups on the backbone of TAPB-OMeTA is essential in facilitating the interlayer shifting process. After further increasing the size of side groups by grafting poly(N-isopropylacrylamide) oligomers to the TAPB-OMeTA backbone via surface-initiated atom transfer radical polymerization (SI-ATRP), we observed a second interlayer shifting and two adsorption steps in the CO2 adsorption isotherm, suggesting tunability of the interlayer shifting process. Density functional theory (DFT) calculations confirm that the quasi-AA stacking structure is energetically preferred over AA stacking under a CO2 atmosphere. These findings demonstrate that 2D COFs can be “soft” porous materials when interacting with gases, providing new opportunities for 2D COFs in gas storage and separation.