Correlating the Influence of Disulfides in Monolayers across Photoelectron Spectroscopy Wettability and Tunneling Charge-Transport

Kumar, Sumit; Soni, Saurabh; Beek, Carlijn L. F. van; Feringa, Ben L.; Rudolf, Petra; Chiechi, Ryan C.

doi:10.1021/jacs.0c06508

Cited by 21 publications

(38 citation statements)

References 72 publications

(128 reference statements)

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“…Returning to the gold analogy, we note that disulfides also form SAMs on Au, first through strong physisorption and then by chemisorption following S–S homolytic bond cleavage, ,,− both under ambient conditions , and under electrochemical control . It is mostly agreed that disulfides are physisorbed first then undergo hemolytic cleavage on Au surfaces forming Au–S bonds . However, on Si, there is no evidence of strong physisorption of sulfur-containing compounds.…”

Section: Introductionmentioning

confidence: 93%

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Covalent Linkages of Molecules and Proteins to Si–H Surfaces Formed by Disulfide Reduction

et al. 2020

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Thiols and disulfides contacts have been, for decades, key for connecting organic molecules to surfaces and nanoclusters as they form self-assembled monolayers (SAMs) on metals such as gold (Au) under mild conditions. In contrast, they have not been similarly deployed on Si owing to the harsh conditions required for monolayers formation. Here, we show that SAMs can be simply formed by dipping Si−H surfaces into dilute solutions of organic molecules or proteins comprising disulfide bonds. We demonstrate that S−S bonds can be spontaneously reduced on Si−H, forming covalent Si−S bonds in the presence of traces of water, and that this grafting can be catalyzed by electrochemical potential. Cyclic disulfide can be spontaneously reduced to form complete monolayers in 1 hour and the reduction can be catalyzed electrochemically to form full surface coverages within 15 minutes. In contrast, the kinetics of SAM formation of the cyclic disulfide molecule on Au was found to be three folds slower than that on Si. It is also demonstrated that dilute thiol solutions can form monolayers on Si−H following oxidation to disulfides under ambient conditions; the supply of too much oxygen, however, inhibits SAM formation. The electron-transfer kinetics of the Si-S enabled SAMs on Si-H is comparable to that on Au SAMs, suggesting that Si−S contacts are electrically transmissive. We further demonstrate the prospective of this spontaneous disulfide reduction by forming a monolayer of protein azurin on a Si-H surface within 1 hour. The direct reduction of disulfides on Si electrodes opens new capabilities for a range of fields, including molecular electronics, for which highly conducting SAM-electrode contacts are necessary, and for emerging fields such as bio-molecular electronics as disulfide linkages could be exploited to wire proteins between Si electrodes, within context of the current Si-based technologies.

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Section: Introductionmentioning

confidence: 93%

“…60 It is mostly agreed that disulfides are physisorbed first then undergo hemolytic cleavage on Au surfaces forming Au−S bonds. 61 However, on Si, there is no evidence of strong physisorption of sulfur-containing compounds.…”

Section: Introductionmentioning

confidence: 99%

Covalent Linkages of Molecules and Proteins to Si–H Surfaces Formed by Disulfide Reduction

et al. 2020

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“…79,114 Although the surface attachment chemistry can vary, thiol-SAMs are not limited to (coinage) metals and will form on semiconductor materials, such as GaAs, [115][116][117] InP, 118,119 MoS 2 , and WSe 2 . 120 Other sulfur-containing groups, such as sulfides, disulfides, [121][122][123][124] and thiocyanates, 125,126 are also capable of forming SAMs. However, despite their versatility over the selection of substrates, thiols and their derivatives do not form SAMs on the surfaces of oxides.…”

Section: A Thiols and Their Derivativesmentioning

confidence: 99%

“…These mixed monolayers were formed in reverse order compared to the fullerene, with SAMs of pure spiropyran being incubated in solutions of short alkanethiols. A detailed study of this process by Kumar et al 124 using XPS revealed that the alkanethiols undergo metathesis with the weakly bound disulfides that anchor the spiropyrans, converting them to metal-thiolate bonds as they reorganize the SAM into a mixed monolayer. This shows that in-place exchange is a generalizable strategy for producing high-quality SAMs by removing disulfides as well as for forming mixed monolayers.…”

Section: Self-assemblymentioning

confidence: 99%

Charge transport through molecular ensembles: Recent progress in molecular electronics

Liu¹,

Soni

Qiu³

et al. 2021

Chemical Physics Reviews

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This review focuses on molecular ensemble junctions in which the individual molecules of a monolayer each span two electrodes. This geometry favors quantum mechanical tunneling as the dominant mechanism of charge transport, which translates perturbances on the scale of bond lengths into nonlinear electrical responses. The ability to affect these responses at low voltages and with a variety of inputs, such as de/protonation, photon absorption, isomerization, oxidation/reduction, etc., creates the possibility to fabricate molecule-scale electronic devices that augment; extend; and, in some cases, outperform conventional semiconductor-based electronics. Moreover, these molecular devices, in part, fabricate themselves by defining single-nanometer features with atomic precision via self-assembly. Although these junctions share many properties with single-molecule junctions, they also possess unique properties that present a different set of problems and exhibit unique properties. The primary trade-off of ensemble junctions is complexity for functionality; disordered molecular ensembles are significantly more difficult to model, particularly atomistically, but they are static and can be incorporated into integrated circuits. Progress toward useful functionality has accelerated in recent years, concomitant with deeper scientific insight into the mediation of charge transport by ensembles of molecules and experimental platforms that enable empirical studies to control for defects and artifacts. This review separates junctions by the trade-offs, complexity, and sensitivity of their constituents; the bottom electrode to which the ensembles are anchored and the nature of the anchoring chemistry both chemically and with respect to electronic coupling; the molecular layer and the relationship among electronic structure, mechanism of charge transport, and electrical output; and the top electrode that realizes an individual junction by defining its geometry and a second molecule-electrode interface. Due to growing interest in and accessibility of this interdisciplinary field, there is now sufficient variety in each of these parts to be able to treat them separately. When viewed this way, clear structure-function relationships emerge that can serve as design rules for extracting useful functionality.

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“…The S2p region is more interesting as it reveals the nature of interactions between the SAM and the gold substrate. Two components are present [29] , [30] : The first at 162 eV attributed to thiol groups chemisorbed on the metal (-S-Au). The second at 163.5 eV corresponding to free thiol groups physisorbed on the surface (-S-H).…”

Section: Resultsmentioning

confidence: 99%

Effect of cavitation intensity control on self-assembling of alkanethiols on gold in room temperature ionic liquids

Naidji

Hallez

Taouil

et al. 2021

Ultrasonics Sonochemistry

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Highlights Ionic liquids were used to sonicate a “non vapor” media. In absence of vapor, cavitation is controlled by gas pressure. Cavitation influences orientation and organization of self-assembled monolayers. Chemical adsorption of molecules is highly activated by cavitation. Chemical adsorption of molecules is not dependent on cavitation intensity.

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Correlating the Influence of Disulfides in Monolayers across Photoelectron Spectroscopy Wettability and Tunneling Charge-Transport

Cited by 21 publications

References 72 publications

Covalent Linkages of Molecules and Proteins to Si–H Surfaces Formed by Disulfide Reduction

Covalent Linkages of Molecules and Proteins to Si–H Surfaces Formed by Disulfide Reduction

Charge transport through molecular ensembles: Recent progress in molecular electronics

Effect of cavitation intensity control on self-assembling of alkanethiols on gold in room temperature ionic liquids

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