Synthesis and Characterization of New Ce(IV)-MOFs Exhibiting Various Framework Topologies

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 [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 4 (BPyDC) 6 ] (BPyDC 2– = 2,2′-bipyridine-5,5′-dicarboxylate), Ce-DUT-67-PZDC [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 4 (PZDC) 4 (OH) 4 (H 2 O) 4 ] (PZDC 2– = 3,5-pyrazoledicarboxylate), Ce-DUT-67-TDC [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 4 (TDC) 4 (OH) 4 (H 2 O) 4 ] (TDC 2– = 2,5-thiophenedicarboxylate), and Ce-MOF-808 [Ce 6 (μ 3 -O) 4 (μ 3 -OH) 4 (BTC) 2 (OH) 6 (H 2 O) 6 ] (BTC 3– = 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 [Ce 6 O 4 (OH) 4 (−CO 2 ) 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 H 2 PZDC and H 2 TDC 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. N 2 sorption experiments reveal large specific surface areas of 2120 m 2 g –1 for Ce-UiO-66-BPyDC and 1725 m 2 g –1 for Ce-MOF-808.