Among their potential applications, metal–organic frameworks (MOFs) emerge as promising alternative electrode materials to overcome the disadvantages of low energy density supercapacitors. Although the potential of MOFs lies in their adjustable pore structure and high surface areas, they possess poor conductivity. In this context, composites with conductive matrices, including organic conductive polymers, have proved to enhance the electrochemical properties of MOFs and their structural stability in the long-term cycling process compared to the pristine MOF. In this study, we have chosen defective zirconium MOF-808 (d-MOF-808) as a porous material because of its resistance to strong acidic media in a postsynthetic modification process. As a conductive agent, polyaniline (PANI) was selected due to its high stability and facile synthesis. The obtained composites of d-MOF-808@PANI at d-MOF/PANI ratios of 15:1, 30:1, and 60:1 increase the charge transport properties compared to the pristine d-MOF-808 and PANI. Electrochemical evaluation of the new hybrid electrode materials was made to demonstrate the capacitance retention. Among the series of materials prepared, the 60:1 composite shows the highest capacitance (188 F/g at 30 mV s–1) in 1 M KOH and a notable capacitance retention of 99.8% for up to 10,000 cycles with 99.7% coulombic efficiency.

(1a) with potentially accessible micropores as demonstrated by single-crystal X-ray diffraction measurements. Electron paramagnetic resonance spectroscopy analysis of 1 has also been assessed.

The hybrid compound [Cu(cyclam)(H 2 O) 2 ] 0.5 [{Cu(cyclam)} 1.5 { B -H 2 As 2 Mo 6 O 26 (H 2 O)}]·9H 2 O ( 1 ) (cyclam = 1,4,8,11-tetraazacyclotetradecane) was synthesized in aqueous solution by reacting the {Cu(cyclam)} 2+ complex with a mixture of heptamolybdate and an arsenate(V) source. Crystal packing of 1 exhibits a supramolecular open-framework built of discrete covalent molybdoarsenate/metalorganic units and additional [Cu(cyclam)(H 2 O) 2 ] 2+ cations, the stacking of which generates squarelike channels parallel to the z axis with an approximate cross section of 10 × 11 Å 2 where all the hydration water molecules are hosted. Thermal evacuation of solvent molecules yields a new anhydrous crystalline phase, but compound 1 does not preserve its single-crystalline nature upon heating. However, when crystals are dehydrated under vacuum, they undergo a structural transformation that proceeds via a single-crystal-to-single-crystal pathway, leading to the anhydrous phase [{Cu(cyclam)} 2 ( A -H 2 As 2 Mo 6 O 26 )] ( 2 ). Total dehydration results in important modifications within the inorganic cluster skeleton which reveals an unprecedented solid-state B to A isomerization of the polyoxoanion. This transition also involves changes in the Cu II bonding scheme that lead to covalent cluster/metalorganic layers by retaining the open-framework nature of 1 . Compound 2 adsorbs ambient moisture upon air exposure, but it does not revert back to 1 , and the hydrated phase [{Cu(cyclam)} 2 ( A -H 2 As 2 Mo 6 O 26 )]·6H 2 O ( 2h ) is obtained instead. Structural variations between 1 and 2 are reflected in electron paramagnetic resonance spectroscopy measurements, and the permanent microporosity of 2 provides interesting functionalities to the system such as the selective adsorption of gaseous CO 2 over N 2 .

Layered structures of flexible mixed-linkers metal-organic frameworks termed IRHs-(4 and 5) (IRH= Institut de Recherche sur l’Hydrogène) were synthesized by mixing cyclam, tetrakis(4-carboxyphenyl)benzene (TCPB), and copper and zinc metal salts...