Cu(I)-Based Metal–Organic Frameworks as Efficient and Recyclable Heterogeneous Catalysts for Aqueous-Medium C–H Oxidation

Abstract

The enantioselective transformation of ubiquitous C–H bonds into valuable CO bonds offers an efficient synthetic approach to construct carbonyl functionalized molecules. However, the grand obstacles in the reaction are the selectivity issues and side reactions under the harsh reaction conditions. In order to overcome the limits, two Cu­(I)-based MOFs {(NEt4)0.5[Cu3(TTPB)0.75(CN)0.5(H2O)]·H2O} n (1) and {[Cu2(TTPB)0.5]·DMF·2H2O} n (2) were synthesized (H4TTPB = 5,5′-(4′,5′-bis­(4-(1H-tetrazol-5-yl)­phenyl)-[1,1′:2′,1′′-terphenyl]-4,4′′-diyl) bis­(1H-tetrazole)) under hydrothermal conditions with (triethylamine (TEA) and ethyldiisopropylamine (DIPEA) as structure-directing agents, respectively. Of these, 1 shows an anionic three-dimensional (3D) framework composed of two kinds of cagelike micropores with 7 × 17 Å and 10 × 17 Å, respectively. In comparison, 2 exhibits a 3D framework with open channels (14 × 8 Å). The stability studies showed that the crystallinity of 1 and 2 could remain in a series of organic solvents (ethanol, N,N-dimethylformamide, chloroform, dioxane, toluene) and acid and alkali aqueous solutions (pH = 1–13) at room temperature for 48 h. 1 and 2 with coordinatively unsaturated Cu­(I) sites were applied as heterogeneous catalysts for the oxidation of arylacycloalkanes in aqueous medium and exhibited excellent catalytic activities, selectivities, and recyclabilities. Moreover, free-radical reaction mechanism and reversible valence-tautomeric conversions of central copper were confirmed during the process by control experiment.

Decarboxylative Oxidation of Carboxylic Acids Using Photocatalysis and Copper Catalysis

“…The product (59 mg, 89% yield) was isolated by eluant EtOAc/PE (1:9) as yellow liquid. The spectra match the reported literature [28] . This article is protected by copyright.…”

Coordination‐Induced N−H Bond Splitting of Ammonia and Primary Amine of CuI−MOFs

“…XPS of the blue samples showed that the high‐resolution Cu 2p spectrum in 3 can be spilt to four peaks, i. e., 962.9, 954.0, 943.4 and 934.1 eV, which are characteristics of divalent copper (Figure 1b). The peaks of 962.9 and 943.4 eV are satellite peaks of Cu 2p 1/2 (954.0 eV) and Cu 2p 3/2 (934.1 eV) [7b,9] . In contrast, XPS of Cu I −MOF 1 displays the binding energy peaks of 951.8 eV (Cu 2p 1/2 ) and 932.0 eV (Cu 2p 3/2 ), indicating Cu I chemical state.…”

Assembly of Two Self-Interpenetrating Metal–Organic Frameworks Based on a Trigonal Ligand: Syntheses, Crystal Structures, and Properties

“…By virtue of abundant N atoms as Lewis basic sites in the framework, MOF 2 can be investigated and implemented to catalyze the Knoevenagel condensation reaction. − The prepared block crystals were soaked in fresh toluene for 30 min and further dried in air for 2 h. In a typical reaction, malononitrile (1.1 mol) and substrates with various functional groups (1.0 mmol) were dissolved in 6 mL of toluene in the presence of MOF 2 (100 mg), which was continually heated at 80 °C for 4 h under slow stirring. The catalytic resultant was measured and calculated by the GC method.…”