Panoscopic Structures by Hierarchical Cascade Self‐Assembly of Inorganic Surfactants with Magnetic Heads Containing Dysprosium Ions

Polarz, Sebastian; Bährle, Christian; Landsmann, Steve; Klaiber, Alexander

doi:10.1002/anie.201303565

Cited by 23 publications

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References 48 publications

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“…Electron spray ionization mass spectrometry (ESIMS) is apowerful tool for investigating the molecular composition of hybrid surfactants. [11,13] Thea nion patterns observed were in agreement with the masses for the deprotonated molecular ions [MC 30 H 55 N 4 O 6 ] À (Figure 1a,b). By ESIMS alone one can not prove with certainty that the metal cation is coordinated as depicted in Scheme 1.…”

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confidence: 79%

“…[11] Then et charge of deprotonated DOTAw as fully neutralized by Dy 3+ ,t hus reducing the surfactant character. [11] Forbetter surfactant-like character,acharged head group is preferred. Thus,D OTA should be coordinated to either M 2+ or to M 4+ .P lenty of redox-stable metal cations M 2+ are available,a nd robust complexes of DOTAe xist also with d-block metals, [12] many of them paramagnetic.Wedescribe herein the series shown in Scheme 1(see Table S1 in the Supporting Information for all compounds prepared for the current study).…”

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

et al. 2017

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Gaining external control over self‐organization is of vital importance for future smart materials. Surfactants are extremely valuable for the synthesis of diverse nanomaterials. Their self‐assembly is dictated by microphase separation, the hydrophobic effect, and head‐group repulsion. It is desirable to supplement surfactants with an added mode of long‐range and directional interaction. Magnetic forces are ideal, as they are not shielded in water. We report on surfactants with heads containing tightly bound transition‐metal centers. The magnetic moment of the head was varied systematically while keeping shape and charge constant. Changes in the magnetic moment of the head led to notable differences in surface tension, aggregate size, and contact angle, which could also be altered by an external magnetic field. The most astonishing result was that the use of magnetic surfactants as structure‐directing agents enabled the formation of porous solids with 12‐fold rotational symmetry.

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

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“…(c) Influence of the head's magnetic moment on surface tension and micellar aggregate size. (d) Aggregates formed by a surfactant containing Dy 3+ oriented in a magnetic field …”

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confidence: 99%

“…The micelles are spherical at B =0 T. However, when the field is turned on, a transition to elongated micelles takes place. Amphiphiles possessing an even higher magnetic moment can be prepared via the reaction with Dy 3+ . The amphiphiles undergo a very unusual, hierarchical self‐assembly process, which ends up in particles at macroscopic dimensions (Figure d).…”

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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

et al. 2017

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Gaining external control over self-organization is of vital importance for future smart materials.S urfactants are extremely valuable for the synthesis of diverse nanomaterials. Their self-assembly is dictated by microphase separation, the hydrophobic effect, and head-group repulsion. It is desirable to supplement surfactants with an added mode of long-range and directional interaction. Magnetic forces are ideal, as they are not shielded in water.W er eport on surfactants with heads containing tightly bound transition-metal centers.T he magnetic moment of the head was varied systematically while keeping shape and charge constant. Changes in the magnetic moment of the head led to notable differences in surface tension, aggregate size, and contact angle,which could also be altered by an external magnetic field. The most astonishing result was that the use of magnetic surfactants as structuredirecting agents enabled the formation of porous solids with 12-fold rotational symmetry.The spontaneous formation of organized patterns as an intrinsic property of asystem containing discrete constituents, ap rocess termed self-assembly,h as fascinated scientists for decades.N ature shows the enormous potential of such behavior, since many of the unexcelled properties of biological matter originate from its capacity for adaptive selfassembly.[1] Full exploration of this potential in materials science is still remote,a smost reported examples of selfassembly so far are dictated by internal factors,s uch as thermodynamic equilibrium.[2] Systems reaching as tate of higher order only under constant consumption of energy (dissipative,n on-equilibrium state) have seldom been reported.[3] Apremise for advancing research in this direction is that compounds capable of adaptive self-assembly can be equipped with the ability to be actuated externally.Examples from particle research, such as dispersions of superparamagnetic colloids, [4] demonstrate the promise of manipulation by the use of magnetism, because it can be applied in astatic or dynamic way,a nd unlike electric fields,m agnetism is not damped in aqueous electrolytes.T hus,i ti sw orth exploring the use of external magnetic fields to trigger the selforganization of molecular systems.As model systems for the self-assembly of soft matter, surfactants are the focus of much current interest. Surfactants are molecular species that contain two moieties of opposite solvent compatibility arranged in adipolar geometry.Inpolar solvents,u sually water, concentration-dependents elf-organization takes place.T he amphiphilic properties of surfactants make them suitable for the stabilization of interfaces of many kinds,f or example,f or the generation of nanoparticles or nanoporous materials.[5] Thetypical head group of surfactants is organic in nature and, thus,d iamagnetic.T om ake as urfactant magnetic, one of its constituents should contain ap aramagnetic metal species.T his emerging field was reviewed very recently by Eastoe and co-workers.[6] Most known examples involve surfac...

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Panoscopic Structures by Hierarchical Cascade Self‐Assembly of Inorganic Surfactants with Magnetic Heads Containing Dysprosium Ions

Abstract: Magnetic moustaches: Inorganic surfactants (I-SURFs) with head groups containing Dy(3+) undergo a hierarchical self-organization cascade controlled by magnetic interactions. The resulting aggregates are shaped like dumbbells with frayed, moustache-like ends.

Cited by 23 publications

References 48 publications

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

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

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

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