We report the structure of the Zr metal− organic frameworks (MOFs) UiO-66 and UiO-67 to very fine detail using synchrotron single-crystal X-ray diffraction and the synthesis method used to obtain single crystals. Zr terephthalate MOF UiO-66 is known to have missing linkers, and the nature of these are shown to be coordinating water and solvent molecules. Single crystals of the isoreticular material UiO-67 does not show such missing linker defects.

Employing high-throughput methods, the synthesis conditions for a series of six new MOFs based on aluminium ions and the V-shaped linker molecule 1,3-benzene dicarboxylic acid, denoted as CAU-10-X (CAU = Christian-Albrechts-University) with the sum formula [Al(OH)(C 8 H 3 O 4 X)]•solvent, were established (X = functional group in 5-position of the aromatic ring; X = H (1), CH 3 (2), OCH 3 (3) NO 2 (4), NH 2 (5), or OH (6)). Due to the absence of macroscopic crystals, the obtained compounds were structurally characterized employing XRPD-methods. The crystal structures of 1, 2 and 3 were refined using Rietveld methods. Although the described MOFs are isoreticular, they crystallize in several, sometimes non-centrosymmetric space groups (1, 4, 6), due to slight structural changes induced by the functionalization. These space groups were confirmed with second-harmonic generation measurements. All compounds are highly stable as confirmed by temperature-dependent XRPD-and IR-experiments and decompose at temperatures above 350 °C. The stabilities of all compounds in aqueous solutions of varying pH were confirmed by XRPD-measurements and their sorption properties towards nitrogen, hydrogen, carbon dioxide and water vapor at low pressures are reported. A drastic influence of the functional group on affinity, capacity and accessibility of the pores for these gases is observed. These properties depend on the polarity and size of the functional group as well as on subtle structural differences between the CAU-10-X compounds.

Aluminium isophthalate CAU-10-H is a promising stable adsorbent for application in heat-exchange processes.

We report on the applicability of an easy general synthesis procedure for the formation of Ce­(IV)-MOFs which contain hexanuclear clusters. Thus, the series of Ce­(IV)-based MOFs isoreticular to their Zr analogues has been extended to reo and spn topologies. Four new MOFs denoted as Ce-UiO-66-BPyDC [Ce6(μ3-O)4(μ3-OH)4(BPyDC)6] (BPyDC2– = 2,2′-bipyridine-5,5′-dicarboxylate), Ce-DUT-67-PZDC [Ce6(μ3-O)4(μ3-OH)4(PZDC)4(OH)4(H2O)4] (PZDC2– = 3,5-pyrazoledicarboxylate), Ce-DUT-67-TDC [Ce6(μ3-O)4(μ3-OH)4(TDC)4(OH)4(H2O)4] (TDC2– = 2,5-thiophenedicarboxylate), and Ce-MOF-808 [Ce6(μ3-O)4(μ3-OH)4(BTC)2(OH)6(H2O)6] (BTC3– = benzene-1,3,5-tricarboxylate) were obtained under mild reaction conditions (100 °C) and after short reaction times (15 min) using a modulated synthesis approach. The MOFs differ in their connectivity of the [Ce6O4(OH)4(−CO2) x ] (x = 12, 8, 6) cluster, the geometry of the organic linker molecules (linear and bent dicarboxylic acids, tricarboxylic acid), and the resulting topology (fcu, reo, spn). The structures of all Ce-MOFs were confirmed using PXRD data by Rietveld refinement and Le Bail fitting. The heterocyclic aromatic dicarboxylic acids H2PZDC and H2TDC lead to MOFs which are both isostructural to DUT-67 due to the similar linker geometries. Ce-UiO-66-BPyDC and Ce-MOF-808 are thermally stable up to 330 and 150 °C, respectively, as proven by VT-PXRD measurements. N2 sorption experiments reveal large specific surface areas of 2120 m2 g–1 for Ce-UiO-66-BPyDC and 1725 m2 g–1 for Ce-MOF-808.