The paddle-wheel type cluster Co(RCOO)(L) (R = substituent group, L = terminal ligand), possessing unusual metal coordination geometry compared with other cobalt compounds, may display high catalytic activity but is highly unstable especially in water. Here, we show that with judicious considerations of the host/guest geometries and modular synthetic strategies, the labile dicobalt clusters can be immobilized and stabilized in a metal-organic framework (MOF) as coordinative guests. The Fe(na)(L) fragment in the MOF [{Fe(μ-O)(bdc)}{Fe(na)(L)}] (Hbdc = 1,4-benzenedicaboxylic acid, Hna = nicotinic acid) can be removed to give [{Fe(μ-O)(bdc)}] with a unique framework connectivity possessing suitable distribution of open metal sites for binding the dicobalt cluster in the form of Co(na)(L). After two-step, single-crystal to single-crystal, postsynthetic modifications, a thermal-, water-, and alkaline-stable MOF [{Fe(μ-O)(bdc)}{Co(na)(L)}] containing the desired dicobalt cluster was obtained, giving extraordinarily high electrocatalytic oxygen evolution activity in water at pH = 13 with overpotential as low as 225 mV at 10.0 mA cm.

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Two-dimensional (2D) materials and ultrathin nanosheets are advantageous for elevating the catalysis performance and elucidating the catalysis mechanism of heterogeneous catalysts, but they are mostly restricted to inorganic or organic materials based on covalent bonds. We report an electrochemical/chemical exfoliation strategy for synthesizing metal-organic 2D materials based on coordination bonds. A catechol functionalized ligand is used as the redox active pillar to construct a pillared-layer framework. When the 3D pillared-layer MOF serves as an electrocatalyst for water oxidation (pH 13), the pillar ligands can be oxidized in situ and removed. The remaining ultrathin (2 nm) nanosheets of the metal-organic layers are an efficient catalyst with overpotentials as low as 211 mV at 10 mA cm and a turnover frequency as high as 30 s at an overpotential of 300 mV.

Reversible chemisorption of CO2is realized by introducing monodentate hydroxide onto the pore surface of metal–organic frameworks.

Using a bis-triazolate ligand and tetrahedral Zn(II) ion, we synthesized a flexible porous coordination polymer functionalized with pairs of uncoordinated triazolate N-donors that can be used as guest chelating sites to give very high CO(2) adsorption enthalpy and CO(2)/N(2) selectivity. The dynamic CO(2) sorption behavior could be monitored well by single-crystal X-ray diffraction.