What Are the "Holes" in Self-Assembled Monolayers of Alkanethiols on Gold?

Schönenberger, Christian; Sondag‐Huethorst, J. A. M.; Jorritsma, J.; Fokkink, L. G. J.

doi:10.1021/la00015a001

Cited by 281 publications

(254 citation statements)

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“…In the case of molecular layers, specific surface patterns were observed. The occurrence of these patterns was attributed to an etching of the bottom gold layers arising from the reaction of the thiol-groups with the gold atoms, forming dissolvable complexes [23][24]. The DNA layers thickness have been investigated using variable angle spectroscopic ellipsometry (VASE, J.A.Woollam & co.) working in rotating analyzer mode.…”

Section: Measurementsmentioning

confidence: 99%

Conductivity of natural and modified DNA measured by scanning tunneling microscopy. The effect of sequence, charge and stacking

Kratochvílová¹,

Král²,

Bunček³

et al. 2008

Biophysical Chemistry

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPT AbstractThe conductivity of DNA covalently bonded to a gold surface was studied by means of the STM technique. Various single-and double-stranded 32-nucleotide-long DNA sequences were measured under ambient conditions so as to provide a better understanding of the complex process of chargecarrier transport in natural as well as chemically modified DNA molecules. The investigations focused on the role of several features of DNA structure, namely the role of the negative charge at the backbone phosphate group and the related complex effects of counterions, and of the stacking interactions between the bases in Watson-Crick and other types of base pairs. The measurements have indicated that the best conductor is DNA in its biologically most relevant double-stranded form with Watson-Crick base pairs and charged phosphates equilibrated with counterions and water. All the studied modifications, including DNA with non-Watson-Crick base pairs, the abasic form, and especially the form with phosphate charges eliminated by chemical modifications, lower the conductivity of natural DNA.

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Section: Measurementsmentioning

confidence: 99%

Conductivity of natural and modified DNA measured by scanning tunneling microscopy. The effect of sequence, charge and stacking

Kratochvílová¹,

Král²,

Bunček³

et al. 2008

Biophysical Chemistry

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“…These experimental parameters were chosen since the Hpyt molecule is quite long and strong interaction with the tip during scanning could take place in a way similar to that observed for long chain alkyl thiols. 26 Low resolution images of the gold sample after self-assembly show a few defects on the terraces. The images of the structure were very transitory because scanning disrupted the molecular layer and higher tunneling resistances could not be reached with the set-up employed.…”

Section: Stm Measurementsmentioning

confidence: 99%

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Paulo

Silva

Pinheiro

et al. 2008

J. Braz. Chem. Soc.

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O composto 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) adsorve espontaneamente sobre ouro formando SAMs ("Self-Assembled Monolayers") que, de acordo com os resultados eletroquímicos e de STM ("Scanning Tunneling Microscopy"), contêm poros através dos quais as moléculas dos complexos [Fe(CN) 6 ] 4-, a dependência da corrente faradáica com o pH da solução eletrolítica permitiu o cálculo do pKa da molécula de Hpyt adsorvida sobre ouro (4,2). Os parâmetros termodinâmicos, H ads and G ads , para o processo de adsorção desta molécula foram estimados em -20,01 e -39,39 kJ mol -1 , respectivamente, utilizando-se o modelo de Langmuir. O processo redox da metaloproteína citocromo c foi estudado utilizando-se a SAM de Hpyt. A constante de velocidade heterogênea de transferência de elétrons foi calculada em 2,29 10 -3 cm s -1 .5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) spontaneously adsorbs on gold forming SAMs (self-assembled monolayers) that, based on STM (Scanning Tunneling Microscopy) and electrochemical data, contain pinholes through which [Fe(CN) 6 ] 4-and [Ru(NH 3 ) 6 ] 3+ probe molecules access the underlying gold electrode. For the former molecule, the dependence of the faradaic current on the electrolyte solution pH value allowed the evaluation of the surface pKa as 4.2. The thermodynamic parameters H ads and G ads for the Hpyt adsorption process could be described by the Langmuir model and were calculated as -20.01 and -39.39 kJ mol -1 , respectively. Electrodic redox reaction of cytochrome c metalloprotein was accessed by using the Hpyt SAM with a heterogeneous electron transfer rate constant of 2.29 10 -3 cm s -1 .

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“…It is now well known that the alkanethiols are arranged in striped structures when the coverage is low [8][9][10] and in a (√3 x √3)R30° or c(4√3 x 2√3) structure with a tilt angle of 30° from the surface normal when the coverage becomes high [11]. STM also revealed that there are many defects in the SAMs such as missing rows and pits [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

Sumi

Wano

Uosaki

2003

Journal of Electroanalytical Chemistry

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The electrochemical characteristics of an Au(111) electrode were investigated in 0.1 M KOH ethanol solutions containing various concentrations of decanethiol. Anodic and cathodic peaks corresponding to the oxidative adsorption and reductive desorption, respectively, of a self-assembled monolayer (SAM) of decanethiol were observed. Both peaks negatively shifted with the increase in the thiol concentration by ca. 57 mV/decade, showing that the redox process is a one-electron process. The adsorbed amount determined from the charge corresponding to the reductive desorption increased with an increase in the decanethiol concentration but never reached the saturated amount as long as the cyclic voltammograms were continuously recorded with the sweep rate of 10 -200 mV s-1. It increased with the holding time at +0.1 V, which was much more positive than the anodic peak potential, and reached the saturated amount in ca. 10 min in the 10 μM thiol solution. The reductive peak potential also negatively shifted with the holding time but for a longer period. It kept shifting for ca. 60 min in the 10 μM thiol solution, which is much longer than the time when the adsorbed amount reached the saturated value. These results suggest that the formation of a highly ordered SAM requires a much longer time than the adsorption of the thiol.2

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What Are the "Holes" in Self-Assembled Monolayers of Alkanethiols on Gold?

Cited by 281 publications

References 0 publications

Conductivity of natural and modified DNA measured by scanning tunneling microscopy. The effect of sequence, charge and stacking

Conductivity of natural and modified DNA measured by scanning tunneling microscopy. The effect of sequence, charge and stacking

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Electrochemical oxidative adsorption and reductive desorption of a self-assembled monolayer of decanethiol on the Au(111) surface in KOH+ethanol solution

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