The enantioselectivity of the manganese-salen complex in the epoxidation of unfunctionalized olefins and the influence of grafting

Bogaerts, Thomas; Wouters, Sebastian; Voort, Pascal Van Der; Speybroeck, Véronique Van

doi:10.1016/j.molcata.2015.05.020

Cited by 7 publications

(1 citation statement)

References 55 publications

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“…Structurally metal-salens are one of the simplest and closest analogues to metalloporphyrins and the active sites of various metallo-enzymes. They are known to mimic enzyme activities (e.g., reversible binding of oxygen), perform catalytic epoxidation (Jacobsen-Katsuki catalysts), − asymmetric Henry reaction, − asymmetric hydrolytic kinetic resolution (HKR), − electrochemical oxygen reduction reaction (ORR), ,, organic oxidations, , etc. For most of all these catalysts, metal-salen-based heterogeneous catalysts are developed by means of its (a) immobilization on silica, zeolite, carbon nanotube, graphitic carbon, graphene oxide, − , (b) incorporation as structural part in metal–organic frameworks (MOFs), covalent organic frameworks (COFs), polymers, etc., ,,− and (c) encapsulation in MOFs, COFs, etc. − …”

Section: Introductionmentioning

confidence: 99%

Efficient Electrocatalytic Water Oxidation by Fe(salen)–MOF Composite: Effect of Modified Microenvironment

et al. 2019

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An efficient and robust heterogeneous electrocatalyst, FSWZ-8 ((Fe-(salen)(OH) + H 4 [SiW 12 O 40 ]•HCl)@ZIF-8) for oxygen evolution reaction (OER) at the neutral pH, was developed by coencapsulation of Fe-salen (i.e., Fe(salen)Cl) and SiW 12 (i.e., H 4 [SiW 12 O 40 ]) inside the cavity of zeolitic imidazolate framework-8 (ZIF-8) material by an in situ synthesis. Here ZIF-8 functions as a host, Fe-salen as the active catalyst, and SiW 12 helps in the charge transport by lowering the overall electrical resistance of the resulting composite system. High turnover frequency (∼5 s −1 ) and high Faradaic efficiency (∼94%) make the concerned composite an efficient catalyst toward water oxidation. This is the first report of one of the simplest known metal complexes, Fe-salen, to perfrom electrocatalytic OER as a heterogeneous catalyst in the neutral pH. This work also highlights the benefits of coencapsulation of the Keggin polyoxometalate (POM) along with the active catalyst Fe-salen species. Encapsulation of SiW 12 results in (i) faster formation of FSWZ-8 composite, (ii) higher loading of Fe-salen, and, most importantly, (iii) lowering of required overpotential for electrochemical OER by more than 150 mV. The Keggin POMs, located as discrete molecular oxides inside the cavity of ZIF-8 as well as on the surface of ZIF-8, facilitate electrical charge conduction in the ZIF-8 matrix and lower the overall charge-transfer resistance.

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Section: Introductionmentioning

confidence: 99%

Efficient Electrocatalytic Water Oxidation by Fe(salen)–MOF Composite: Effect of Modified Microenvironment

et al. 2019

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Heterogeneous Asymmetric Catalysis

Mastalir

Bartók

2017

Handbook of Solid State Chemistry

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This chapter summarizes the results on asymmetric reactions induced by supported or immobilized chiral organocatalysts, collected in reviews before 2008 and also in more recent papers published between 2009 and 2015. The most extensively studied asymmetric reactions are as follows: aldol addition, Michael reaction, Diels‐Alder reaction, diethylzinc addition, epoxidation, and hydrogenation. The most important support materials used for the fabrication of immobilized chiral organocatalysts are natural or synthetic polymers, amorphous and ordered silica, cross‐linked polymers, clays, inorganic materials, nanoparticles (NPs) and metal‐organic frameworks (MOFs) with various structural features. The asymmetric aldol reaction is one of the most efficient synthetic methods for obtaining optically active β‐hydroxy carbonyl compounds, which may be applied in organic syntheses. The enantioselective Michael addition is one of the most frequently studied reactions in asymmetric organocatalysis, which is suitable for the construction of optically active compounds that are useful intermediates for a number of natural and synthetic products.

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Mechanistic Investigation on Oxygen Transfer with the Manganese‐Salen Complex

et al. 2015

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The best‐known application of salen complexes is the use of a chiral ligand loaded with manganese to form the Jacobsen complex. This organometallic catalyst is used in the epoxidation of unfunctionalized olefins and can achieve very high selectivities. Although this application was proposed many years ago, the mechanism of oxygen transfer remains a question until now. In this paper, the epoxidation mechanism is investigated by an ab initio kinetic modeling study. First of all a proper DFT functional is selected that yields the correct ordering of the various spin states. Our results show that the epoxidation proceeds via a radical intermediate. If we start from the radical intermediate, these results can explain the experiments with radical probes. The subtle influences in the transition state using the full Jacobsen catalyst explain the product distribution observed experimentally.

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The enantioselectivity of the manganese-salen complex in the epoxidation of unfunctionalized olefins and the influence of grafting

Cited by 7 publications

References 55 publications

Efficient Electrocatalytic Water Oxidation by Fe(salen)–MOF Composite: Effect of Modified Microenvironment

Efficient Electrocatalytic Water Oxidation by Fe(salen)–MOF Composite: Effect of Modified Microenvironment

Heterogeneous Asymmetric Catalysis

Mechanistic Investigation on Oxygen Transfer with the Manganese‐Salen Complex

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