Magneto‐Adaptive Surfactants Showing Anti‐Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12‐Fold Symmetry

Hermann, Stefanie; Wessig, Martin; Kollofrath, Dennis; Gerigk, Melanie; Hagedorn, Kay; Odendal, James A.; Hagner, Matthias; Drechsler, Markus; Erler, Philipp; Fonin, Mikhail; Maret, Georg; Polarz, Sebastian

doi:10.1002/anie.201612416

Cited by 10 publications

(9 citation statements)

References 44 publications

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“…First, 2,6‐dichloro‐4‐iodopyridine ( 2 ) was coupled to the alkyl‐substituted phenylboronic acid ( 1 ) by means of Suzuki coupling, followed by the nucleophilic substitution of the chlorine substituents in 3 with an N ‐substituted imidazole ( 4 ). Because the flexible alkyl chain prevents growing single‐crystals and characterization by X‐ray diffraction methods, electron‐spray ionization mass spectrometry (ESIMS) has proven to be a valuable method for hybrid surfactants . The ESIMS patterns of 5 a,b are shown in the Supporting Information, Figure S1.…”

Section: Methodsmentioning

confidence: 99%

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

Donner

Hagedorn

Mattes

et al. 2017

Chemistry A European J

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Processing of substrates with different solvent compatibility is a persistent problem in homogeneous catalysis, in particular when one starting compound is water soluble and the other is not. A promising concept reported in the literature is micellar catalysis. However, the process of developing catalysts that are surfactants at the same time is still in its early stages. We report the synthesis of a new surfactant system with an N‐heterocyclic carbene (NHC) moiety as a head group. Characteristic surfactant properties such as the formation of micelles or liquid crystals is documented. The new surfactant ligand forms coordination compounds with various metals, most importantly Pd2+, in square planar geometry. In addition, the Pd‐NHC compound shows surfactant features, and can be used successfully for C−C cross‐coupling reactions (Suzuki, Heck). The boost in catalytic activity by one order of magnitude compared to analogous but non‐amphiphilic species is reported.

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Section: Methodsmentioning

confidence: 99%

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

Donner

Hagedorn

Mattes

et al. 2017

Chemistry A European J

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“…Recently, more and more papers describe advanced surfactants with properties beyond simple amphiphilic properties . Our group has specialized in the synthesis of surfactants equipped with functional, metal‐containing head groups, and several examples of catalytically active surfactants have already been published by us . Important preliminary work of relevance to the current work is centered on fullerene‐based surfactants that evaluated their self‐assembly behavior and the related beneficial effect of self‐assembly on their properties …”

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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“… (a) Synthesis of DOTA‐based, magnetic surfactants . (b) Structure of the surfactant after metal cation (M 2+ ) coordination.…”

Section: Influencing Surfactant Self‐assembly By Physical Triggersmentioning

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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Magneto‐Adaptive Surfactants Showing Anti‐Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12‐Fold Symmetry

Cited by 10 publications

References 44 publications

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

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

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

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