Dendronized Ferromagnetic Gold Nanoparticles Self‐Organized in a Thermotropic Cubic Phase

Donnio, Bertrand; Garcia-Vazquez, Patricia; Gallani, Jean‐Louis; Guillon, Daniel; Terazzi, Emmanuel

doi:10.1002/adma.200701252

Cited by 130 publications

(115 citation statements)

References 42 publications

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“…The ligand-exchange reaction did not affect mean diameter of NPs but slightly increased metallic core size distribution (4.7±0.6 nm; as determined with TEM). It should be noticed that the free compound L does not form LC phases and melts directly into the isotropic phase at B87°C, but mesogenic properties of the ligand are not prerequisite for inducing SA of NPs into the LC phase 59,60 . Also, molecules with similar architecture to L, comprising three aromatic rings with ester linkages, were reported to support formation of LC phases 61 .…”

Section: Resultsmentioning

confidence: 99%

Dynamically self-assembled silver nanoparticles as a thermally tunable metamaterial

et al. 2015

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The availability of metamaterials with properties that can be actively tuned is crucial for the future development of various metamaterial-based technologies. Here we show that by using silver nanoparticles equipped with a thermally responsive organic coating a metamaterial is obtained with reversibly switchable properties. The material investigated exhibits dynamic self-assembly resulting from temperature-dependent changes of organic coating shape, which translates to a switchable spatial distribution of the silver nanoparticles. This in turn strongly influences the optical properties of the entire material. The measured optical characteristics of the material are in excellent agreement with theoretical calculations, which allow us to use the latter to predict a dynamically tunable epsilon-near-zero behaviour of the metamaterial. The suggested methodology opens new routes for tunable metamaterials that operate in the visible region and will enable various applications for soft-matter-based optical devices.

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Section: Resultsmentioning

confidence: 99%

Dynamically self-assembled silver nanoparticles as a thermally tunable metamaterial

et al. 2015

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“…9 On the other hand, the magnetic character of gold NPs is probably their most intriguing property, 21 as noble metals are diamagnetic in their bulk phases. In the last years several experimental groups have reported the appearance of a magnetic polarization in ligand-coated gold NPs [22][23][24][25][26][27] mainly based on superconducting quantum interference device (SQUID) or X-ray magnetic circular dichroism (XMCD) measurements. Still, there is a wealth of contradictory experimental results about the size of the magnetic moments, their origin or the ferromagnetic character of the particles.…”

Section: Introductionmentioning

confidence: 99%

A first principles study of thiol-capped Au nanoparticles: Structural, electronic, and magnetic properties as a function of thiol coverage

Cuadrado

Puerta

Soria

et al. 2013

The Journal of Chemical Physics

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We have studied the stability of thiolated Au 38 nanoparticles (NPs) via density functional theory based calculations varying the coverage from 0 up to 32 molecules. Three different initial core arrangements were considered for the cluster, spherical, tubular, and bi-icosahedral, while thiol groups were attached to the cluster via the sulfur atom either as single molecules or forming more complex staple motifs. After molecular dynamics runs several metastable configurations are found at each coverage thus allowing to analyze the properties of the NPs in the form of ensemble averages. In particular, we address the structural and electronic properties as a function of the number of thiols. The study emphasizes the strong influence of the core structure on the stability of the NPs, and its interplay with the thiol coverage and adsorption geometries. The magnetic properties of the NPs have also been explored via spin-polarized calculations including spin-orbit coupling. No evidence for the existence of a robust intrinsic ferromagnetism is found in any of the structures. © 2013 AIP Publishing LLC. [http://dx

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“…Only in one case, the mesophase displayed by the materials could be identified [4]: an enantiotropic nematic phase was obtained for gold nanoparticles partly decorated with laterally-branched mesogens; the latter ligands showed a monotropic nematic phase. Alternatively, gold nanoparticles were partly functionalized with non-mesomorphic second-generation poly(benzyl ether) dendrons [5] also via a ligand-exchange reaction to give an enantiotropic Im3m cubic phase.…”

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confidence: 99%

Liquid‐Crystalline Thiol‐ and Disulfide‐Based Dendrimers for the Functionalization of Gold Nanoparticles. Preliminary Communication

Frein

Boudon

Vonlanthen

et al. 2008

Helvetica Chimica Acta

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Liquid-crystalline dendrons carrying either a thiol or disulfide function which display nematic, smectic A, columnar, or chiral nematic phases have been synthesized. Their mesomorphic properties are in agreement with the nature of the mesogenic units and structure of the dendrons. The first-generation poly(aryl ester) dendron containing two cyanobiphenyl mesogenic units was used to functionalize gold nanoparticles. For full coverage, a smectic-like supramolecular organization on the nanometer scale is observed, when the gold nanoparticles are spread onto carbon-coated copper grids. This result indicates that the dendritic ligands reported here act as self-organization promoters.Introduction. -Rational design of novel supramolecular materials for applications in optics, electronics, catalysis, and biomedical sciences is still a challenge [1], current interest with this aim being focused on the synthesis of thermotropic liquid-crystalline gold nanoparticles [2 -5]. Decorated gold nanoparticles are one of the most promising candidates for self-organization leading to bulk metamaterials, i.e., materials with nonconventional electromagnetic properties. It has already been shown that regular arrangements of metallic particles on different length scales can lead to negative magnetic permeability [6]. This opens the pathway to metamaterials in the visible light region, provided that the following conditions are fulfilled: the distance and organization of the particles have to be controlled, and there should be a possibility to compensate optical absorption by incorporation of active agents to allow energy transfer [7]. The first condition is fulfilled by the self-organization within the liquidcrystal phase itself, while the second one can be fulfilled by adding fluorescence dyes into the liquid-crystal materials.To generate mesomorphism, gold nanoparticles were functionalized with liquidcrystalline thiol derivatives [2 -4] via a ligand-exchange reaction from dodecane-1-thiol-stabilized gold nanoparticles [8]. Only in one case, the mesophase displayed by the materials could be identified [4]: an enantiotropic nematic phase was obtained for gold nanoparticles partly decorated with laterally-branched mesogens; the latter

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Dendronized Ferromagnetic Gold Nanoparticles Self‐Organized in a Thermotropic Cubic Phase

Cited by 130 publications

References 42 publications

Dynamically self-assembled silver nanoparticles as a thermally tunable metamaterial

Dynamically self-assembled silver nanoparticles as a thermally tunable metamaterial

A first principles study of thiol-capped Au nanoparticles: Structural, electronic, and magnetic properties as a function of thiol coverage

Liquid‐Crystalline Thiol‐ and Disulfide‐Based Dendrimers for the Functionalization of Gold Nanoparticles. Preliminary Communication

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