Cerium-based metal organic frameworks with UiO-66 architecture: synthesis, properties and redox catalytic activity

Abstract

A series of nine Ce(iv)-based metal organic frameworks with the UiO-66 structure containing linker molecules of different sizes and functionalities were obtained under mild synthesis conditions and short reaction times. Thermal and chemical stabilities were determined and a Ce-UiO-66-BDC/TEMPO system was successfully employed for the aerobic oxidation of benzyl alcohol.

Influence of the pH on the Condensation of Tetravalent Cerium Cations in Association with [α‐SiW9O34]10– Leading to the Formation of a Ce6O4(OH)4 Core

“…It is embedded in a cavity available in the tungsten ribbon by six bonds with oxygen atoms of the ribbon and four bonds with bridging µ 3 ‐O atoms of the hexamer. As far as we know, this hexanuclear core bearing three different coordination spheres is different from those observed in the literature where all six atoms of the cluster are in a square antiprismatic geometry . Due to the low quality of the structure, only one independent sodium cation was localized, giving four related sodium atoms in the molecular compound.…”

Solvent Impact on the Properties of Benchmark Metal–Organic Frameworks: Acetonitrile‐Based Synthesis of CAU‐10, Ce‐UiO‐66, and Al‐MIL‐53

“…2) Ce‐UiO‐66 [Ce 6 O 4 (OH) 4 (BDC) 6 ] represents the redox‐active cerium‐based analogue of Zr‐UiO‐66 and contains hexanuclear cerium‐oxygen clusters ([Ce 6 O 4 (OH) 4 ] 12+ ) (BDC 2− : terephthalate). Each cluster is coordinated to 12 other clusters via terephthalate ions, which leads to a fcu topology (Figure , bottom left) . 3) Al‐MIL‐53 [Al(OH)(BDC)], a MOF composed of infinite chains of trans corner‐sharing AlO 6 octahedra that are interconnected by terephthalate ions, represents a special type of framework.…”

“… Structures of CAU‐10 (top left), Ce‐UiO‐66 (bottom left), as well as narrow‐ (top right) and open‐pore form (bottom right) of standard Al‐MIL‐53 with unit cell edges. AlO 6 octahedra are shown in light blue and Ce 6 O 32 polyhedra in light orange.…”

“…Here, we present the syntheses of CAU‐10, Ce‐UiO‐66, and Al‐MIL‐53 from acetonitrile as well as the characterization of the products with a special focus on changes of the framework flexibility of Al‐MIL‐53.…”

Metal–Organic Frameworks as Catalysts for Oxidation Reactions

“…In contrast to the behavior of benzyl alcohol, efforts to oxidize 1‐phenylethanol and diphenylcarbinol with Cu MOFs and TEMPO failed, even at 120 °C after 16 h. This higher reactivity of primary versus secondary benzylic alcohols follows general trends for many solid catalysts and indicates that the active sites are spatially encumbered. Recently, among a series of nine Ce IV ‐based MOFs with the UiO‐66 structure with linker molecules having different sizes and functionalities, Ce‐UiO‐66‐bdc/TEMPO catalyzed the aerobic oxidation of benzyl alcohol with 88 % conversion after 24 h at 110 °C . In another example, UiO‐66‐Sal‐CuCl 2 was reported to promote the aerobic oxidation of benzyl alcohol in the presence of TEMPO reaching 99 % conversion and selectivity at 60 °C after 24 h .…”