Supported heteropolyanions as solid counterions for the electrostatic immobilization of chiral copper complexes

Torviso, M. Rosario; Blanco, Mirta N.; Cáceres, Carmen Victoria; Fraile, José M.; Mayoral, José A.

doi:10.1016/j.jcat.2010.07.017

Cited by 24 publications

(4 citation statements)

References 43 publications

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“…(ii) The acidity/basicity value of the reaction systems in hydrothermal environments might influence the reduction of Cu(II) . (iii) The types of polyoxoanions and countercations can also influence the transformation of different oxidation states of the transition metal. , Thus, during synthesizing POMCPs 1 and 2 , the 4-(1 H -tetrazol-5-yl)pyridine ligand may act as the reducing agent to reduce Cu(II) to Cu(I) ions with a pH value of 1.5–2.0 under hydrothermal conditions. However, the Cu(II) ions in compounds 3 and 4 are not reduced by the N-donor ligands.…”

Section: Results and Discussionsupporting

confidence: 77%

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Chang

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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Selective oxidation of alkyl-substituted phenols offers efficient access to p-benzoquinones (BQs) that serve as key components for synthesizing biologically active compounds, but rational manufacture of efficient recyclable catalysts for such a reaction remains a severe challenge. Herein, two crystalline 2D polyoxometalate-based coordination polymers (POMCPs), formulated as H3[CuI 3(L)3]2[PM12O40]·xH2O (M = Mo, x = 4 for 1; M = W, x = 6 for 2; and HL = 4-(1H-tetazol-5-yl)pyridine), are prepared by a mineralizer-assisted one-step synthesis strategy and explored as heterogeneous catalysts for p-BQs synthesis. Both compounds have been characterized through elemental analysis, EDS analysis, infrared spectroscopy, UV–vis diffuse reflectance spectrum, EPR, XPS, BET, single-crystal, and powder X-ray diffraction. Single-crystal X-ray diffraction analysis indicates that both 1 and 2 exhibit an interesting 2D sheet structure composed of 2-connected Keggin type anions [PM12O40]3– and hexa-nuclear {CuI 6(HL)6} cluster-based metal–organic chains via Cu···O interactions. When used as catalysts, POMCPs 1 and 2 have excellent catalytic activities in the selective oxidation of substituted phenols to p-BQs with H2O2. Notedly, in the model reaction from 2,3,6-trimethylphenol (TMP) to the vitamin E key intermediate trimethyl-p-benzoquinone (TMBQ), the catalytic activities expressed by turnover frequency (TOF) of 1 and 2 can reach an unprecedented 2400 and 2000 h–1, respectively, at close to 100% TMBQ yield. The truly heterogeneous nature, stability, and structural integrity of both catalysts were ascertained by FTIR, PXRD techniques, and the following cycles. Mechanism studies reveal that both catalysts can involve a dual reaction pathway through a heterolytic oxygen atom transfer mechanism and homolytic radical mechanism. Moreover, the 2D POMCPs with highly accessible bilateral active sites and efficient mass transfer efficiency possess superior catalytic performance to their analogous 3D species.

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Section: Results and Discussionsupporting

confidence: 77%

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Chang

Chen

et al. 2021

ACS Appl. Mater. Interfaces

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“…Phosphomolybdic acid (H 3 PMo 12 O 40 , PMA), phosphotungstic acid (H 3 PW 12 O 40 , PTA), silicomolybdic acid (H 4 SiMo 12 O 40 , SMA), and tungstosilicic acid (H 4 SiW 12 O 40 , STA) are the four most commonly utilized polyoxometalates with Keggin structure. Additionally all of them have been loaded onto supports as heterogeneous catalysts in previous studies. ,− The oxygen-enriched Keggin structure endows each polyoxometalate molecule with various anchoring sites for metal atoms with different coordinating environments . However, provided that each metal atom interacts with one polyoxometalate by staying on the most stable site, polyoxometalate offers a good platform for designing SACs with uniform structure.…”

Section: Resultsmentioning

confidence: 99%

Atomically Dispersed Pt₁–Polyoxometalate Catalysts: How Does Metal–Support Interaction Affect Stability and Hydrogenation Activity?

et al. 2019

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Unlike nano-structured metal catalysts, supported single-atom catalysts (SACs) contain only atomically dispersed metal atoms hinting at much more pronounced metal-support effects.Herein, we take a series of polyoxometalates supported Pt catalysts as examples to quantitatively investigate the stability of Pt atoms on oxide supports and how the Pt-support interaction influences the catalytic performance. For this entire series, we show that the Pt atoms prefer to stay at a four-fold hollow site of one polyoxometalate molecule, and that the least adsorption energy to obtain sintering resistant Pt SACs is 5.50 eV, which exactly matches the cohesive energy of bulk Pt metal. Further, we compared their catalytic performance in several hydrogenation reactions and simulated the reaction pathways of propene hydrogenation by density functional theory calculations. Both experimental and theoretical approaches 2 suggest that despite the Pt 1 -support interactions being different, the reaction pathways of various Pt1-polyoxometalate catalysts are very similar and their effective reaction barriers are close to each other and as low as 24 kJ/mol, indicating the possibility of obtaining SACs with improved stability without compromising activity. DFT calculations show that all reaction elementary steps take place only on the Pt atom without involving neighboring O atoms, and that hydrogenation proceeds from the molecularly adsorbed H 2 species. Pt-SAC give a weaker H 2 adsorption energy than Pt clusters or surfaces, resulting in small adsorption equilibrium constants and small apparent activation barriers which agree between experiment and theory.

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“…In 2010, Fraile et al prepared a Cu–PW 12 /SiO 2 catalyst via loading bis(oxazoline)–copper complexes onto a [PW 12 O 40 ] 3− carrier. 85 Compared with the Cu precursor, the supported heterogeneous catalyst exhibits higher activity and stability toward the cyclopropanation reaction, with high yields (of up to 97%) and enantioselectivities in the range of 82–96% for trans -cyclopropane over six catalytic cycles. In 2013, a Ru(BINAP)–PW 12 /Al 2 O 3 catalyst was developed following a similar procedure.…”

Section: Supported Pom Sacsmentioning

confidence: 99%

Polyoxometalate-based materials: quasi-homogeneous single-atom catalysts with atomic-precision structures

Liu

Wang

2022

J. Mater. Chem. A

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Supported heteropolyanions as solid counterions for the electrostatic immobilization of chiral copper complexes

Cited by 24 publications

References 43 publications

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Atomically Dispersed Pt₁–Polyoxometalate Catalysts: How Does Metal–Support Interaction Affect Stability and Hydrogenation Activity?

Polyoxometalate-based materials: quasi-homogeneous single-atom catalysts with atomic-precision structures

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Supported heteropolyanions as solid counterions for the electrostatic immobilization of chiral copper complexes

Cited by 24 publications

References 43 publications

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Highly Efficient Synthesis of p-Benzoquinones Catalyzed by Robust Two-Dimensional POM-Based Coordination Polymers

Atomically Dispersed Pt1–Polyoxometalate Catalysts: How Does Metal–Support Interaction Affect Stability and Hydrogenation Activity?

Polyoxometalate-based materials: quasi-homogeneous single-atom catalysts with atomic-precision structures

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Product

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Atomically Dispersed Pt₁–Polyoxometalate Catalysts: How Does Metal–Support Interaction Affect Stability and Hydrogenation Activity?