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By using the strategy of pre-assembly chlorosulfonation applied to a linker precursor, the first sulfonated zirconium metal-organic framework (JUK-14) with twodimensional (2D) structure, was synthesized. Single-crystal Xray diffraction reveals that the material is built of Zr 6 O 4 (OH) 4 (COO) 8 oxoclusters, doubly 4-connected by angular dicarboxylates, and stacked in layers spaced 1.5 nm apart by the presence of sulfonic groups. JUK-14 exhibits excellent hydrothermal stability, permanent porosity confirmed by gas adsorption studies, and shows high (> 10 À 4 S/cm) and low (< 10 À 8 S/cm) proton conductivity under humidified and anhydrous conditions, respectively. Post-synthesis inclusion of imidazole improves the overall conductivity increasing it to 1.7 × 10 À 3 S/cm at 60 °C and 90 % relative humidity, and by 3 orders of magnitude at 160 °C. The combination of 2D porous nature with robustness of zirconium MOFs offers new opportunities for exploration of the material towards energy and environmental applications.

Terminal sulfonic acid groups characterize various proton conducting materials including metal-organic frameworks (MOFs). These groups, however, show strong coordination ability that hinders their direct intact incorporation. We present a strategy...

Four new layered flexible metal–organic frameworks (MOFs) containing a diacylhydrazone moiety, namely, guest-filled [Zn 2 (iso) 2 (tdih) 2 ] n ( 1 ), [Zn 2 (NH 2 iso) 2 (tdih) 2 ] n ( 2 ), [Cd 2 (iso) 2 (tdih) 2 ] n ( 3 ) and [Cd 2 (NH 2 iso) 2 (tdih) 2 ] n ( 4 ) were synthesized using terephthalaldehyde di-isonicotinoylhydrazone ( tdih ) as a linear ditopic linker as well as isophtalate (iso) or 5-aminoisophthalate (NH 2 iso) as angular colinkers. The MOFs with hexacoordinated cadmium centers feature two-dimensional pore systems as compared to the MOFs with pentacoordinated zinc centers showing either zero-dimensional or mixed zero-/one-dimensional voids, as evidenced by single-crystal X-ray diffraction. In contrast to the frameworks based on isophtalates which do not show any significant gas uptakes, introduction of amino-substituted linker enables CO 2 adsorption. Gently activated aminoisophthalate-based frameworks, that is, guest-exchanged in methanol and heated to 100 °C, show reversible gated CO 2 adsorptions at 195 K, whereas the increase of activation temperature to 150 °C or more leads to one-step isotherms and lower adsorption capacities. X-ray diffraction and IR spectroscopy reveal significant structural differences in interlayer hydrogen bonding upon activation of materials at higher temperatures. The work emphasizes the role of hydrogen bonds in crystal engineering of layered materials and the importance of activation conditions in such systems.