Three-Dimensional Silver-Containing Polyoxotungstate Frameworks for Photocatalytic Aerobic Oxidation of Benzyl Alcohol

Abstract

Photocatalytic organic transformation derived by functionalized polyoxometalate (POM)-based metal−organic frameworks provides a feasible route for fine chemical synthesis. Herein, three kinds of photoactive threedimensional silver-containing polyoxotungstate frameworks are synthesized with the formulasIn compounds 1−3, the cationic Ag−triazole clusters with diverse nuclei serve as nodes to assemble with rigid bridging ligands (L) and polyoxoanions to extend into stable three-dimensional frameworks, in which Keggin-type anions act as guests or pendants. When using them as heterogeneous photocatalysts, compounds 1−3 show high catalytic activity and selectivity for the photocatalytic aerobic oxidation of benzyl alcohol to benzoic acid under 10 W 365 nm light irradiation. Among them, compound 1 exhibits the highest performance with ca. 99% benzyl alcohol conversion and 99% selectivity of benzoic acid in 9 h. Compounds 2 and 3 show ca. 79 and 88% conversions of benzyl alcohol, respectively, which are higher than those of the individual Keggin-type precursors. Moreover, mechanism investigation suggests that the synergistic cooperation occurring between cationic Ag−triazole clusters and Keggin-type polyoxoanions modulates the energy band structures of compounds 1−3, resulting in the efficient separation of photogenerated carriers and accelerating the aerobic oxidation of benzyl alcohol. This work provides some important guidance for the design and development of efficient POM-based photocatalysts for practical organic transformation.

Two 3D Two-Fold Interpenetrated Dia-Like Polyoxometalate-Based Metal–Organic Frameworks: Synthesis and Sulfide Selective Oxidation Activity

“…The asymmetric unit cell of 1 consists of half of a polyoxometalate anion [PMo 10 VI Mo 2 V O 40 ] 3‑ (abbreviated as PMo 12 ), one crystallization-independent Co II ion, two independent btap ligands, and two water molecules, with their coordinated modes shown in Figure . The central P atom of PMo 12 anion is surrounded by a cube of eight oxygen atoms with each site half-occupied, which is a normal phenomenon in the Keggin-based structure . The bond valence calculation sum expresses that there is one Mo atom in the +5 oxidation state and the Co atom is in the +2 oxidation state in the asymmetric unit (Table S3).…”

Anticancer Drug Extraction from Plasma Samples Using Three-Dimensional Polyoxometalate-Based Supramolecular Frameworks as Sorbents

“…Currently, one promising approach for designing such functionalized materials has been proposed, wherein the coordination properties of POMs are combined with various metal–organic coordination compounds to produce crystalline inorganic–organic hybrid structures based on POMs. , In the resulting high-dimensional supramolecular networks or metal–organic frameworks (MOF), POMs are either coordinated to oxophilic metal centers through metal–oxygen coordination bonds or connected as an anionic template via noncovalent interactions. POMs made from inorganic–organic hybrid materials combine the advantages of inorganic POMs with the capabilities of metal–organic elements which make them more valuable for many promising potential applications. − In fact, during the synthesis of these hybrids, it was difficult to control and predict the nuclearity and dimensionality of the resultant architectures. In this regard, the reactants (POMs, metal ions, and organic ligands) must be carefully chosen when constructing inorganic–organic hybrids based on POMs.…”

CsPbBr3/Polyoxometalate Composites for Selective Photocatalytic Oxidation of Benzyl Alcohol

“…In addition, Poblet and co-workers reported a three-component hybrid material {[g-CN]/H 3 POM/[Re 1 –Re 2 ]} consisting of graphitic carbon nitride (g-CN), a phosphotungstate POM [PW 12 O 40 ] 3– , and a dimeric rhenium catalyst {[Re 1 (bipyNNH 2 )-(CO) 3 Cl–Re 2 (bipy)­(CO) 3 Cl], bipy = 2,2′-bipyridine} acting as a visible light photosensitive semiconductor, an electron/proton switch, and the [Re­(I)] CO 2 reduction catalyst, where H 3 POM acted as the electrons and protons shuttle between the photosensitive g-CN, organic substrate, and Re 1 –Re 2 catalyst, leading to an enhanced catalytic activity toward the CO 2 photoreduction reaction . For the selective oxidation of alcohol reaction, the POM-based composite photocatalysts have also been reported but still facing some problems such as the use of UV light source, the addition of additional oxidant, and the lower selectivity. − Therefore, it is highly desirable to develop visible light-responsive and efficient POM-based composites toward the photooxidation of benzyl alcohol to benzaldehyde.…”