Place Exchange Reactions of Alkyl Thiols on Gold Nanoparticles

Kassam, Adil; Bremner, Glen; Clark, Brad; Ulíbarri, Gerardo; Lennox, R. Bruce

doi:10.1021/ja057091q

Cited by 118 publications

(128 citation statements)

References 22 publications

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“…The inset in Figure 5b shows the plot of the NBT peak versus the MBT peak, which appears almost linear, indicating a one-to-one displacement exchange between the two thiols. 29,30 It is noted that the only difference between the two molecules in this case is the nature of their para substituent, which is electron donating in the case of methoxybenzenethiol and electron withdrawing for nitrobenzenethiol. Hence the results suggest that the background depends on the electronic structure of the molecule and its resulting interaction with the metal surface as well as being dependent on both plasmons and adsorbate coverage.…”

Section: Resultsmentioning

confidence: 99%

Understanding the Surface-Enhanced Raman Spectroscopy “Background”

et al. 2009

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Even 35 years after the discovery of surface-enhanced Raman spectroscopy (SERS) much remains to be learned about the phenomenon.1-3 Despite broad consensus on the mechanism of SERS, many features remain poorly understood and in particular much less effort has been put into understanding the continuum emission called the "background" observed in SERS spectra. Here the SERS background is studied systematically on sphere segment void (SSV) plasmonic substrates. We establish the physicochemical dependence of the background on plasmons, the identity of the adsorbate, adsorbate coverage and electrochemical potential. In particular, by exchanging electron-donating and electron-withdrawing adsorbates, we demonstrate predictable modulation of the SERS background. Using these observations, we propose a model for the origin of the SERS background. Finally, we test the proposed model against its predictions for anti-Stokes SERS spectra.

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Section: Resultsmentioning

confidence: 99%

Understanding the Surface-Enhanced Raman Spectroscopy “Background”

et al. 2009

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“…Gas chromatography has been applied to detect the exchange of one alkylthiol for another of different length, a reaction that is invisible to NMR and fluorescence monitoring techniques. 53 NMR 54 and a more sensitive electron paramagnetic resonance technique 55 have been used to monitor a more complex reaction: the exchange of ligands between differently functionalized NPs in solution.…”

Section: Place-exchange On Nanoparticlesmentioning

confidence: 99%

Divalent Metal Nanoparticles

DeVries

Brunnbauer

et al. 2007

Science

607

534

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Metal nanoparticles hold promise for many scientific and technological applications, such as chemical and biological sensors, vehicles for drug delivery, and subdiffraction limit waveguides. To fabricate such devices, a method to position particles in specific locations relative to each other is necessary. Nanoparticles tend to spontaneously aggregate into ordered two-and three-dimensional assemblies, but achieving onedimensional structures is less straightforward. Because of their symmetry, nanoparticles lack the ability to bond along specific directions. Thus, the technological potential of nanoparticles would be greatly enhanced by the introduction of a method to break the interaction symmetry of nanoparticles, thus inducing valency and directional interparticle interactions.When a nanoparticle is coated with a mixture of two different ligands, the ligands have been shown to phase-separate into ordered domains encircling or spiraling around the core. Topological constraints inherent in assembling two-dimensional vectors (e.g., ligands) onto a sphere (the core of the nanoparticle) dictate the necessary formation of two diametrically opposed defect points within the ligand shell. The molecules at these points are not optimally stabilized by intermolecular interactions and thus these sites are highly reactive. By functionalizing the polar singularities with a third type of molecule, we generate divalent nanoparticles with "chemical handles" that can be used to direct the assembly of the particles into chains. For example, taking inspiration from the wellknown interfacial polymerization synthesis of nylon, we place carboxylic acid terminated molecules at the polar defect points and join the newly bifunctional nanoparticles into chains by reacting them with 1,6-diaminohexane through an interfacial reaction.Furthermore, we perform a full kinetic and thermodynamic characterization of the molecularly defined polar defect points. We demonstrate that the rate of place-exchange at these points is significantly faster than it is elsewhere in the ligand shell. We also determine the equilibrium constant and standard free energy of the place-exchange reaction at the polar defect sites and demonstrate that the reaction is strongly affected by the molecular environment, i.e. the composition of the ligand shell.

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“…II; Scheme 7). From the point of view of functionalization, the direct method [8] leads to full coverage of the nanoparticles surface with the desired thiol derivative; on the other hand, the ligandexchange reaction [17] allows to control the loading of the desired thiol derivative on the gold surface. In this preliminary study, both reactions were carried out with ligand 1.…”

mentioning

confidence: 99%

“…4. Thermal-polarized optical micrograph of the texture displayed by 8 in the nematic chiral phase upon cooling the sample from the isotropic liquid to 998 Scheme 6), and 2) the ligand-exchange reaction [17] (! II; Scheme 7).…”

mentioning

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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Place Exchange Reactions of Alkyl Thiols on Gold Nanoparticles

Cited by 118 publications

References 22 publications

Understanding the Surface-Enhanced Raman Spectroscopy “Background”

Understanding the Surface-Enhanced Raman Spectroscopy “Background”

Divalent Metal Nanoparticles

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

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