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Developing highly stable porous coordination polymers (PCPs) with integrated electrical conductivity is crucial for advancing our understanding of electrocatalytic mechanisms and the structure–activity relationship of electrocatalysts. However, achieving this goal remains a formidable challenge because of the electrochemical instability observed in most PCPs. Herein, we develop a "modular design" strategy to construct electrochemically stable semiconducting PCP, namely, Fe‐pyNDI, which incorporates a chain‐type Fe‐pyrazole metal cluster and π‐stacking column with effective synergistic effects. The three‐dimensional electron diffraction (3D ED) technique resolves the precise structure. Both theoretical and experimental investigation confirms that the π‐stacking column in Fe‐pyNDI can provide an efficient electron transport path and enhance the structural stability of the material. As a result, Fe‐pyNDI can serve as an efficient model electrocatalyst for nitrate reduction reaction (NO3RR) to ammonia with a superior ammonia yield of 339.2 μmol h−1 cm−2 (14677 μg h−1 mgcat.−1) and a faradaic efficiency of 87 % at neutral electrolyte, which is comparable to state‐of‐the‐art electrocatalysts. The in‐situ X‐ray absorption spectroscopy (XAS) reveals that during the reaction, the structure of Fe‐pyNDI can be kept, while part of the Fe3+ in Fe‐pyNDI was reduced in situ to Fe2+, which serves as the potential active species for NO3RR. [ABSTRACT FROM AUTHOR]

We report that linker ligand substitution involving just one atom induces a shape‐memory effect in a flexible coordination network. Specifically, whereas SIFSIX‐23‐Cu, [Cu(SiF6)(L)2]n, (L=1,4‐bis(1‐imidazolyl)benzene, SiF62−=SIFSIX) has been previously reported to exhibit reversible switching between closed and open phases, the activated phase of SIFSIX‐23‐CuN, [Cu(SiF6)(LN)2]n (LN=2,5‐bis(1‐imidazolyl)pyridine), transformed to a kinetically stable porous phase with strong affinity for CO2. As‐synthesized SIFSIX‐23‐CuN, α, transformed to less open, γ, and closed, β, phases during activation. β did not adsorb N2 (77 K), rather it reverted to α induced by CO2 at 195, 273 and 298 K. CO2 desorption resulted in α′, a shape‐memory phase which subsequently exhibited type‐I isotherms for N2 (77 K) and CO2 as well as strong performance for separation of CO2/N2 (15/85) at 298 K and 1 bar driven by strong binding (Qst=45–51 kJ/mol) and excellent CO2/N2 selectivity (up to 700). Interestingly, α′ reverted to β after re‐solvation/desolvation. Molecular simulations and density functional theory (DFT) calculations provide insight into the properties of SIFSIX‐23‐CuN. [ABSTRACT FROM AUTHOR]

Due to the structural complexity and limited controllability of conventional microwave‐absorption materials (MAMs), the precise regulation of atomically‐resolved structures and properties of MAMs remains a significant challenge. The interpretation of the dielectric loss mechanism is usually conduction and polarization losses, while the absence of components‐regulated template materials further hinders the disclosure of the mechanism. Herein, based on the customizable functionality of the MOF platform, a series of pristine bimetallic MOFs with precise and controllable conductivity are successfully constructed through the bimetallic alloying strategy. The controllability is attributed to the alteration of free‐carrier concentration and the subtle difference of interlayer displacement or spacing, both of which originate from the atomic tuning of hetero‐metal. Notably, Cu1.3Ni1.7(HITP)2 features an ultra‐high absorption strength (reflection loss, RL = −71.5 dB) and an ultra‐wide maximum bandwidth (6.16 GHz) at only 15% filling, which ranked in the upper range of all reported MAMs. Due to the metal co‐synergies, Cu1.3Ni1.7(HITP)2 possesses a switchable high absorption peak in a wide range (4–18 GHz). This work opens up an avenue for tailoring the atomic tuning of new MOF‐based electromagnetic wave absorbers and provides a conceptually novel platform. [ABSTRACT FROM AUTHOR]

The separation of C2H2/C2H4 is a challenging task, and adsorptive separation based on porous materials offers a promising energy-efficient alternative. Porous coordination polymers (PCPs) have been advocated as potential adsorbents with high separation performance (adsorption capacity and selectivity) by precisely tuning their pore size and chemistry. However, to achieve the goal of green chemistry and pioneer PCPs for practical applications, not only the separation performance but also low regeneration energy and synthetic cost are crucial factors. We herein prepared a novel PCP TJE-1 with rational distribution of cooperative supramolecular interaction sites, exhibiting a very high C2H2 uptake of 5.27 mmol g−1, and a C2H2 selective adsorption over C2H4 under 1 bar, at 298 K. Theoretical calculations indicate that the selectivity originates from the difference in hydrogen bonding and π interactions, resulting in a low isosteric heat of adsorption for C2H2 (35.5 kJ mol−1). Moreover, TJE-1 also remains stable in aqueous acid/base solutions and can be synthesized with scaling up using economical precursors (about $1.45 per g and $0.13 per g for two ligands). This strategy offers guidance on the development of next-generation PCPs with integrated performance that is highly beneficial for industrial gas separations. [ABSTRACT FROM AUTHOR]

Porous sorbents are materials that are used for various applications, including storage and separation. Typically, the uptake of a single gas by a sorbent decreases with temperature, but the relative affinity for two similar gases does not change. However, in this study, we report a rare example of "crossover sorption," in which the uptake capacity and apparent affinity for two similar gases reverse at different temperatures. We synthesized two soft porous coordination polymers (PCPs), [Zn2(L1)(L2)2]n (PCP‐1) and [Zn2(L1)(L3)2]n (PCP‐2) (L1= 1,4‐bis(4‐pyridyl)benzene, L2=5‐methyl‐1,3‐di(4‐carboxyphenyl)benzene, and L3=5‐methoxy‐1,3‐di(4‐carboxyphenyl)benzene). These PCPs exhibits structural changes upon gas sorption and show the crossover sorption for both C2H2/CO2 and C2H6/C2H4, in which the apparent affinity reverse with temperature. We used in situ gas‐loading single‐crystal X‐ray diffraction (SCXRD) analysis to reveal the guest inclusion structures of PCP‐1 for C2H2, CO2, C2H6, and C2H4 gases at various temperatures. Interestingly, we observed three‐step single‐crystal to single‐crystal (sc‐sc) transformations with the different loading phases under these gases, providing insight into guest binding positions, nature of host–guest or guest‐guest interactions, and their phase transformations upon exposure to these gases. Combining with theoretical investigation, we have fully elucidated the crossover sorption in the flexible coordination networks, which involves a reversal of apparent affinity and uptake of similar gases at different temperatures. We discovered that this behaviour can be explained by the delicate balance between guest binding and host–guest and guest‐guest interactions. [ABSTRACT FROM AUTHOR]