Hybrid Surfactants with <i>N</i>‐Heterocyclic Carbene Heads as a Multifunctional Platform for Interfacial Catalysis

Donner, Adrian; Hagedorn, Kay; Mattes, Lorenz; Drechsler, Markus; Polarz, Sebastian

doi:10.1002/chem.201703902

Cited by 29 publications

(22 citation statements)

References 40 publications

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“…Later, they utilized these two complexes as efficient catalysts in the Mizoroki–Heck and Sonogashira coupling reactions, as well as in the Hiyama coupling between trimethyloxyphenylsilane and aryl bromides in alkaline aqueous medium . The catalytic efficiency of functionalized pincer‐type palladium complex 84 (TOF=3.6×10 −2 s −1 ) was found to be one order of magnitude higher than that of the nonfunctionalized complex 85 (TOF=2.5×10 −3 s −1 ) in the aqueous‐phase coupling of 4‐bromoacetophenone with phenylboronic acid . This enhancement was attributed to the surfactant features of complex 84 , and the reaction was thought to proceed through micellar catalysis.…”

Section: Homogeneous Catalysismentioning

confidence: 97%

“…[58] The catalytic efficiency of functionalized pincer-type palladium complex 84 (TOF = 3.6 10 À2 s À1 ) was found to be one order of magnitude higher than that of the nonfunctionalized complex 85 (TOF = 2.5 10 À3 s À1 )i nt he aqueous-phasec oupling of 4-bromoacetophenone with phenylboronicacid. [59] This enhancement was attributed to the surfactantf eatures of complex 84,a nd the reactionw as thought to proceed through micellar catalysis. Tu and co-workerss ynthesized ah ydrophilic carboxylic acid functionalized palladium complex 86,w ith benzimidazol-2-ylidened onors,w hichw as found to catalyze the coupling reaction under extremely low catalystl oadings on the ppm scale (8 10 À6 mol %) with TON = 7.625 10 6 .…”

Section: Suzuki-miyaura Reactionmentioning

confidence: 99%

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Chelating Bis(N‐Heterocyclic Carbene) Palladium‐Catalyzed Reactions

Liu

Gou

Han

2018

Chemistry An Asian Journal

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N-Heterocyclic carbenes (NHCs) have been widely employed in the construction of various metal complexes and applied in the field of catalysis. In this review, a series of palladium complexes comprising chelating bis(NHC) donors (Pd-bis(NHC) complexes) are outlined according to their application in homogeneous catalysis. Examples of metal-organic frameworks containing Pd-bis(NHC) moieties are briefly discussed, in terms of their use in heterogeneous catalysis. The catalytic applications of Pd-bis(NHC) complexes (or moieties in heterogeneous catalysts) are mainly focused on the Mizoroki-Heck, Suzuki-Miyaura, and Sonogashira coupling reactions. Another 14 types of reactions are also summarized beyond these three types of reactions.

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Section: Homogeneous Catalysismentioning

confidence: 97%

Section: Suzuki-miyaura Reactionmentioning

confidence: 99%

Chelating Bis(N‐Heterocyclic Carbene) Palladium‐Catalyzed Reactions

Liu

Gou

Han

2018

Chemistry An Asian Journal

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“…It is also possible to use solvents that would normally not be suitable for such reaction. These aggregates can be formed by supporting compounds that do not take place in the reaction themselves or by the catalyst molecule . The phrase supramolecular catalysis is manly known from reactions with enzymatic systems which can catalyze reaction via weak interactions within their structural motif.…”

Section: Figurementioning

confidence: 99%

Aggregation‐Induced Improvement of Catalytic Activity by Inner‐Aggregate Electronic Communication of Metal‐Fullerene‐Based Surfactants

et al. 2020

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A paradigm for active constituents in (homogeneous) catalysis is that optimum performance requires maximum dispersion. Generally, aggregation results in a decline. This is a different case in supramolecular catalysis. A new concept based on surfactants equipped with functional heads is presented, which becomes a more active catalyst itself upon aggregation. The head group of the surfactants is composed of a diethylenetriamine-functionalized fullerene capable of coordinating to catalytically active metals like Co II . The improvement of catalytic properties upon aggregation is demonstrated via electrocatalytic water-splitting reaction as a model system. Detailed electrochemistry studies were performed at concentrations below and above the critical aggregation concentration (cac). While isolated surfactant molecules represent only moderately active catalysts, drastic improvement of efficiency in the hydrogen evolution (HER) as well as in the oxygen evolution reactions (OER) were detected, once vesicular structures have formed. Self-organization of the surfactants leads to an increase in turnover frequencies of up to 1300 % (HER). The strongly beneficial effect of aggregation arises from the favorable alignment of individual molecules, thus, facilitating intermolecular charge transfer processes in the vesicles.In many cases, aggregation is seen as a major drawback for catalytic reactions since upon aggregation the number of accessible reactive centers is reduced and a maximum of dispersion, especially for heterogeneous systems was the goal to achieve. Research perspective changed and systems have been developed in which aggregation comes hand in hand with beneficial effects. The field of self-assembled compounds, the supramolecular chemistry gives rise to supramolecular catalysis. In micellar catalysis, the formation of aggregates is used to perform reactions at their interface with compounds that would otherwise not be combinable. It is also possible to use solvents that would normally not be suitable for such reaction. These aggregates can be formed by supporting compounds that do not take place in the reaction themselves or by the catalyst molecule. [1][2][3] The phrase supramolecular catalysis is manly known from reactions with enzymatic systems which can catalyze reaction via weak interactions within their structural motif. Furthermore, this field describes the assembly of small-molecule organic catalysts. [4][5] This very assembly of the catalyst influences the reactants in a way that reactive moieties are exposed and activated, intermediates or transition states are stabilized or that the reactivity is enhanced by increasing the local concentration of the reactants. [6][7][8] In this work, we present a new concept of supramolecular catalysis that does not influence the reactant's properties but the catalyst itself. This is achieved by a catalytically active surfactant. Surfactants are molecular compounds with amphiphilic properties, which form well-defined aggregates. Depending on concentration, individual su...

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“…In several publications, the authors show that the product selectivity in the Miyaura–Michael reaction can be improved in comparison to using conventional, non‐amphiphilic catalysts . Our group has recently presented a surfactant containing an N ‐heterocyclic carbene (NHC) head . The coordination to Pd led to a system that was able to catalyse Suzuki coupling reactions much faster than a non‐amphiphilic reference system.…”

Section: Catalytic Surfactantsmentioning

confidence: 99%

“…[41] Our group has recently presented a surfactant containing an N-heterocyclic carbene (NHC) head. [42] The coordination to Pd led to as ystem that was able to catalyse Suzukic oupling reactions much faster than an on-amphiphilic reference system.…”

Section: Catalytic Surfactantsmentioning

confidence: 99%

Added‐Value Surfactants

Polarz

Kunkel

Donner

et al. 2018

Chemistry A European J

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Surfactants are ubiquitous in cellular membranes, detergents or as emulsification agents. Due to their amphiphilic properties, they cannot only mediate between two domains of very different solvent compatibility like water and organic but also show fascinating self-assembly features resulting in micelles, vesicles, or lyotropic liquid crystals. The current review article highlights some approaches towards the next generation surfactants, for example, those with catalytically active heads. Furthermore, it is shown that amphiphilic properties can be obtained beyond the classical hydrophobic-hydrophilic interplay, for instance with surfactants containing one molecular block with a special shape. Whereas, classical surfactants are static, researchers have become more interested in species that are able to change their properties depending on external triggers. The article discusses examples for surfactants sensitive to chemical (e.g., pH value) or physical triggers (temperature, electric and magnetic fields).

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Hybrid Surfactants with N‐Heterocyclic Carbene Heads as a Multifunctional Platform for Interfacial Catalysis

Cited by 29 publications

References 40 publications

Chelating Bis(N‐Heterocyclic Carbene) Palladium‐Catalyzed Reactions

Chelating Bis(N‐Heterocyclic Carbene) Palladium‐Catalyzed Reactions

Aggregation‐Induced Improvement of Catalytic Activity by Inner‐Aggregate Electronic Communication of Metal‐Fullerene‐Based Surfactants

Added‐Value Surfactants

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