Self-Assembled Monolayers Derived from Alkoxyphenylethanethiols Having One, Two, and Three Pendant Chains

Rittikulsittichai, Supachai; Jamison, Andrew C.; Lee, T. Randall

doi:10.1021/la201313g

Cited by 11 publications

(23 citation statements)

References 67 publications

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“…Much of what we know derives from extensive structure-function relationships of alkane thiolate SAMs on gold surfaces [204]. In these systems, a higher ligand surface density and longer alkyl chains yield closer alkane-alkane packing and stronger van der Waals interactions that prevent solutes from diffusing to the substrate surface that can etch or degrade the underlying nanocrystal or ligand [80, 205].…”

Section: Surface Engineering For Biomedical Applicationsmentioning

confidence: 99%

Quantum dot surface engineering: Toward inert fluorophores with compact size and bright, stable emission

Lim

Schleife

et al. 2016

Coordination Chemistry Reviews

109

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The surfaces of colloidal nanocrystals are complex interfaces between solid crystals, coordinating ligands, and liquid solutions. For fluorescent quantum dots, the properties of the surface vastly influence the efficiency of light emission, stability, and physical interactions, and thus determine their sensitivity and specificity when they are used to detect and image biological molecules. But after more than 30 years of study, the surfaces of quantum dots remain poorly understood and continue to be an important subject of both experimental and theoretical research. In this article, we review the physics and chemistry of quantum dot surfaces and describe approaches to engineer optimal fluorescent probes for applications in biomolecular imaging and sensing. We describe the structure and electronic properties of crystalline facets, the chemistry of ligand coordination, and the impact of ligands on optical properties. We further describe recent advances in compact coatings that have significantly improved their properties by providing small hydrodynamic size, high stability and fluorescence efficiency, and minimal nonspecific interactions with cells and biological molecules. While major progress has been made in both basic and applied research, many questions remain in the chemistry and physics of quantum dot surfaces that have hindered key breakthroughs to fully optimize their properties.

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Section: Surface Engineering For Biomedical Applicationsmentioning

confidence: 99%

Quantum dot surface engineering: Toward inert fluorophores with compact size and bright, stable emission

Lim

Schleife

et al. 2016

Coordination Chemistry Reviews

109

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“…This method is not compatible with nonradiolabeled SAMs. Other methods to estimate coverage include in-plane X-ray diffraction, helium diffraction, scanning tunneling microscopy (STM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), − and cyclic voltammetry of redox tagged SAMs. − The diffraction and proximal probe techniques provide the crystalline unit cell structure for well-ordered SAMs, from which the large area coverage is then inferred. These analyses indicate that well-ordered alkyl thiol SAMs form epitaxial overlayers on Au (111) with the √3 × √3 R 30° unit cell structure; the corresponding surface coverage on Au is thus 4.6 molecules/nm 2 .…”

mentioning

confidence: 99%

Quantitative Surface Coverage Measurements of Self-Assembled Monolayers by Nuclear Reaction Analysis of Carbon-12

Demissie

Haugstad

Frisbie

2016

J. Phys. Chem. Lett.

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We report surface coverage measurements by Rutherford backscattering spectrometry (RBS) of self-assembled monolayers (SAMs) of both alkyl thiols and oligophenylene thiols on Au-coated mica, Si, and pyrolytic graphite. The 12C atom concentration was probed at 4.266 MeV 2 4He2+ primary beam energy, which enhances the 2 4He2+ scattering cross section by exciting 12C nuclear resonance states; this is a submode of RBS commonly referred to as nuclear reaction analysis (NRA). The surface coverage of 12C increased linearly with the number of 12C atoms in each SAM. The consistency of the 12C atom coverage values obtained by NRA was cross-checked by measuring the 32S atom concentration by conventional RBS. From these data, we obtained an average coverage of 3.5 ± 0.2 molecules/nm2 for both alkyl thiols and oligophenylene thiols on polycrystalline Au surfaces. The results show the utility of NRA for quantitative analysis of SAM coverage on Au.

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“…The densely packed SAMs derived from F8H10SH and those from F8H10-C10 exhibit a binding energy of 284.7 eV, while the SAMs derived from F8H10-C12 and F8H10-C18 exhibit values of 284.5 eV and 284.4 eV, respectively. The lower binding energies of the F8H10-C12 and F8H10-C18 SAMs compared to the F8H10SH and F8H10-C10 SAMs are indicative of a lower hydrocarbon chain packing density in the former films [ 78 ]. Furthermore, the shift to lower binding energies in the F8H10-C12 and F8H10-C18 SAMs as the length of the hydrocarbon chain is increased can be plausibly attributed to phase-incompatible fluorocarbon-hydrocarbon interactions in these films.…”

Section: Resultsmentioning

confidence: 99%

Unsymmetrical Spiroalkanedithiols Having Mixed Fluorinated and Alkyl Tailgroups of Varying Length: Film Structure and Interfacial Properties

et al. 2018

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A custom-designed series of unsymmetrical spiroalkanedithiols having tailgroups comprised of a terminally fluorinated chain and a hydrocarbon chain of varying lengths were synthesized and used to prepare self-assembled monolayers (SAMs) on gold substrates. The specific structure of the adsorbates was of the form [CH3(CH2)n][CF3(CF2)7(CH2)8]C[CH2SH]2, where n = 7, 9, and 15 (designated as F8H10-C10, F8H10-C12, and F8H10-C18, respectively). The influence of the length of the hydrocarbon chain in the bidentate dithiol on the structure and interfacial properties of the monolayer was explored. A structurally analogous partially fluorinated monodentate alkanethiol and the corresponding normal alkanethiols were used to generate appropriate SAMs as reference systems. Measurements of ellipsometric thickness showed an unexpectedly low film thickness for the SAMs derived from the bidentate adsorbates, possibly due to disruptions in interchain packing caused by the fluorocarbon chains (i.e., phase-incompatible fluorocarbon-hydrocarbon interactions), ultimately giving rise to loosely packed and disordered films. Analysis by X-ray photoelectron spectroscopy (XPS) were also consistent with a model in which the films were loosely packed; additionally, the XPS spectra confirmed the attachment of the sulfur headgroups of the bidentate adsorbates onto the gold substrates. Studies of the SAMs by polarization modulation-infrared reflection-adsorption spectroscopy (PM-IRRAS) suggested that as the length of the hydrocarbon chain in the adsorbates was extended, a more ordered surface was achieved by reducing the tilt of the fluorocarbon segment. The wettability data indicated that the adsorbates with longer alkyl chains were less wettable than those with shorter alkyl chains, likely due to an increase in interchain van der Waals forces in the former.

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Self-Assembled Monolayers Derived from Alkoxyphenylethanethiols Having One, Two, and Three Pendant Chains

Cited by 11 publications

References 67 publications

Quantum dot surface engineering: Toward inert fluorophores with compact size and bright, stable emission

Quantum dot surface engineering: Toward inert fluorophores with compact size and bright, stable emission

Quantitative Surface Coverage Measurements of Self-Assembled Monolayers by Nuclear Reaction Analysis of Carbon-12

Unsymmetrical Spiroalkanedithiols Having Mixed Fluorinated and Alkyl Tailgroups of Varying Length: Film Structure and Interfacial Properties

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