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Porous molecular crystals sustained by hydrogen bonds and/or weaker connections are an intriguing type of adsorbents, but they rarely demonstrate efficient adsorptive separation because of poor structural robustness and tailorability. Herein, we report a porous molecular crystal based on hydrogen‐bonded cyclic dinuclear AgI complex, which exhibits exceptional hydrophobicity with a water contact angle of 134°, and high chemical stability in water at pH 2–13. The seemingly rigid adsorbent shows a pore‐opening or nonporous‐to‐porous type butane adsorption isotherm and complete exclusion of isobutane, indicating potential molecular sieving. Quantitative column breakthrough experiments show slight co‐adsorption of isobutane with an experimental butane/isobutane selectivity of 23, and isobutane can be purified more efficiently than for butane. In situ powder/single‐crystal X‐ray diffraction and computational simulations reveal that a trivial guest‐induced structural transformation plays a critical role. [ABSTRACT FROM AUTHOR]

Cobalt imidazolate frameworks are classical electrocatalysts for the oxygen evolution reaction (OER) but suffer from the relatively low activity. Here, a non‐3d metal modulation strategy is presented for enhancing the OER activity of cobalt imidazolate frameworks. Two isomorphous frameworks [Co4(MO4)(eim)6] (M=Mo or W, Heim=2‐ethylimidazole) having Co(eim)3(MO4) units and high water stabilities were designed and synthesized. In different neutral media, the Mo‐modulated framework coated on a glassy carbon electrode shows the best OER performances (1 mA cm−2 at an overpotential of 210 mV in CO2‐saturated 0.5 m KHCO3 electrolyte and 2/10/22 mA cm−2 at overpotential of 388/490/570 mV in phosphate buffer solution) among non‐precious metal catalysts and even outperforms RuO2. Spectroscopic measurements and computational simulations revealed that the non‐3d metals modulate the electronic structure of Co for optimum reactant/product adsorption and tailor the energy of rate‐determining step to a more moderate value. [ABSTRACT FROM AUTHOR]