Self-Assembled Monolayers of 6-Phenyl-n-hexanethiol and 6-(p-Vinylphenyl)-n-hexanethiol on Au(111):  An Investigation of Structure, Stability, and Reactivity

and, Lili Duan; Garrett, Simon J.

doi:10.1021/la001633u

Cited by 24 publications

(26 citation statements)

References 39 publications

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“…The IR spectrum exhibited characteristic peaks of aromatic and aliphatic C–H stretching vibrations (see section S1 of the Supporting Information), with no detectable effect of the heteroatom. Aromatic C–H stretch peaks were observed at 3030 and 3070 cm –1 , in agreement with past findings for similar monolayers. ,, An aliphatic C–H antisymmetric stretch peak was observed at 2929 ± 1 cm –1 . This value is 10 cm –1 higher (blue-shifted) than that of a well-packed 16-carbon long alkyl monolayers on a reduced silicon surface, indicating weak interactions between neighboring chains, which is reasonable for alkyl chains consisting of no more than three methylene units .…”

Section: Resultssupporting

confidence: 92%

“…Aromatic C–H stretch peaks were observed at 3030 and 3070 cm –1 , in agreement with past findings for similar monolayers. ,, An aliphatic C–H antisymmetric stretch peak was observed at 2929 ± 1 cm –1 . This value is 10 cm –1 higher (blue-shifted) than that of a well-packed 16-carbon long alkyl monolayers on a reduced silicon surface, indicating weak interactions between neighboring chains, which is reasonable for alkyl chains consisting of no more than three methylene units . This underscores the importance of the interactions between the phenyl rings as those that drive the ordering of the MLs (see NEXAFS results below).…”

Section: Resultssupporting

confidence: 92%

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Effect of Internal Heteroatoms on Level Alignment at Metal/Molecular Monolayer/Si Interfaces

et al. 2018

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Molecular monolayers at metal/semiconductor heterointerfaces affect electronic energy level alignment at the interface by modifying the interface's electrical dipole. On a free surface, the molecular dipole is usually manipulated by means of substitution at its external end. However, at an interface such outer substituents are in close proximity to the top contact, making the distinction between molecular and interfacial effects difficult. To examine how the interface dipole would be influenced by a single atom, internal to the molecule, we used a series of three molecules of identical binding and tail groups, differing only in the inner atom: aryl vinyl ether (PhO), aryl vinyl sulfide (PhS), and the corresponding molecule with a CH 2 groupallyl benzene (PhC). Molecular monolayers based on all three molecules have been adsorbed on a flat, oxide-free Si surface. Extensive surface characterization, supported by density functional theory calculations, revealed high-quality, well-aligned monolayers exhibiting excellent chemical and electrical passivation of the silicon substrate, in all three cases. Current−voltage and capacitance−voltage analysis of Hg/PhX (X = C, O, S)/Si interfaces established that the type of internal atom has a significant effect on the Schottky barrier height at the interface, i.e., on the energy level alignment. Surprisingly, despite the formal chemical separation of the internal atom and the metallic electrode, Schottky barrier heights were not correlated to changes in the semiconductor's effective work function, deduced from Kelvin probe and ultraviolet photoemission spectroscopy on the monolayer-adsorbed Si surface. Rather, these changes correlated well with the ionization potential of the surface-adsorbed molecules. This is interpreted in terms of additional polarization at the molecule/metal interface, driven by potential equilibration considerations even in the absence of a formal chemical bond to the top Hg contact.

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Section: Resultssupporting

confidence: 92%

Section: Resultssupporting

confidence: 92%

Effect of Internal Heteroatoms on Level Alignment at Metal/Molecular Monolayer/Si Interfaces

et al. 2018

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“…Aryl-halide molecules for self-assembly on gold and ITO substrates were synthesized (Chart ). For self-assembled monolayers (SAMs) on gold (molecules 1 and 2 ), an eight-carbon aliphatic chain allows the formation of a well-packed monolayer due to thermodynamically favorable van der Waals interactions, even in the presence of bulky aryl groups . Polarization-modulation infrared reflection–absorption spectroscopy (PM-IRRAS) was used to demonstrate aliphatic stretching frequencies characteristic of a crystalline-like interface (Figure S1, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Surface-Confined Nickel Mediated Cross-Coupling Reactions: Characterization of Initiator Environment in Kumada Catalyst-Transfer Polycondensation

Sontag¹,

Sheppard²,

Usselman³

et al. 2011

Langmuir

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Kumada catalyst-transfer polycondensation (KCTP) has proven to be an excellent strategy toward the synthesis of well-defined conjugated polymers. In this report, Ni(0) species are reacted with surface-bound aryl bromides to yield KCTP initiators of structure (aryl)Ni(II)-Br. Surface-confined Kumada reactions are carried out with a ferrocene functionalized Grignard reagent to quantify initiator coverage, ligand exchange, and Kumada reaction kinetics. In addition, surface-initiated Kumada catalyst-transfer polycondensation (SI-KCTP) is carried out from the fabricated initiators to modify SiO(2) and ITO surfaces. Uniform poly(3-methylthiophene) films with thicknesses between 40 and 65 nm were characterized using a variety of spectroscopic and electrochemical techniques.

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“…The bands at 3084 and 2984 cm À1 are attributed to the asymmetric (n a (QCH 2 )) and symmetric CH 2 (n s (QCH 2 )) stretching modes of the QCH 2 group. 52 The four other spectral features at 3008, 1644, 994 and 914 cm À1 are due to the b C-H stretch of -HCQCH 2 (n(H-CQCH 2 )), the CQC stretch (n(CQC)), the CQC out-of-plane deformation (CQC oop def ), and the QCH 2 out-of-plane deformation (o(QCH 2 )), respectively. 53,54 The wavenumbers and corresponding mode assignments for the RAIR spectrum are provided in Table 1.…”

Section: Initial H 2 Cq Q Qch-sam Characterization By Rairsmentioning

confidence: 99%

Gas-surface reactions of nitrate radicals with vinyl-terminated self-assembled monolayers

Zhang

Chapleski

et al. 2014

Phys. Chem. Chem. Phys.

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Interfacial reactions between gas-phase nitrate radicals, a key nighttime atmospheric oxidant, and a model unsaturated organic surface have been investigated to determine the reaction kinetics and probable reaction mechanism. The experimental approach employs in situ reflection-absorption infrared spectroscopy (RAIRS) to monitor bond rupture and formation while a well-characterized effusive flux of NO3 impinges on the organic surface. Model surfaces are created by the spontaneous adsorption of vinyl-terminated alkanethiols (HS(CH2)16CHCH2) onto a polycrystalline gold substrate. The H2C=CH-terminated self-assembled monolayers provide a well-defined surface with the double bond positioned precisely at the gas-surface interface. The surface reaction kinetics obtained from RAIRS revealed that the consumption rate of the terminal vinyl groups is nearly identical to the formation rate of a surface-bound nitrate species and implies that the mechanism is one of direct addition to the vinyl group rather than hydrogen abstraction. Upon nitrate radical collisions with the surface, the initial reaction probability for consumption of carbon-carbon double bonds was determined to be (2.3 ± 0.5) × 10(-3). This reaction probability is approximately two orders of magnitude greater than the probability of ozone reactions on the same surface, which suggests that oxidation of surface-bound vinyl groups by nighttime nitrate radicals may play an important role in atmospheric chemistry despite their relatively low concentration.

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Self-Assembled Monolayers of 6-Phenyl-n-hexanethiol and 6-(p-Vinylphenyl)-n-hexanethiol on Au(111): An Investigation of Structure, Stability, and Reactivity

Cited by 24 publications

References 39 publications

Effect of Internal Heteroatoms on Level Alignment at Metal/Molecular Monolayer/Si Interfaces

Effect of Internal Heteroatoms on Level Alignment at Metal/Molecular Monolayer/Si Interfaces

Surface-Confined Nickel Mediated Cross-Coupling Reactions: Characterization of Initiator Environment in Kumada Catalyst-Transfer Polycondensation

Gas-surface reactions of nitrate radicals with vinyl-terminated self-assembled monolayers

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