• Title/Summary/Keyword: Self Assembled Monolayers

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Self-Assembled Monolayers of Alkanethiols on Clean Copper Surfaces

  • Sung, Myung M.;Kim, Yeon Su
    • Bulletin of the Korean Chemical Society
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    • v.22 no.7
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    • pp.748-752
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    • 2001
  • Alkanethiols (CH3(CH2)n-1SH) based self-assembled monolayers (SAMs) on the clean copper surfaces have been examined for n = 4, 8, and 16. Using X-ray photoelectron spectroscopy (XPS) and contact angle analysis, it is found that alkanethiolate monolayers similar to those on gold are formed on clean copper surfaces. The monolayers are stable in air up to about 140 $^{\circ}C.$ Above 160 $^{\circ}C$ the monolayers begin to desorb through the oxidation reaction of the thiolate to sulfonate, with the alkyl chains remaining intact. Following this desorption step, the copper surface has begun to oxidize to CuO at about 180 $^{\circ}C$.

Study on Morphology Investigation and Charge-transfer Property of Self-assembled Viologen Monolayers (자기조립된 Viologen 단분자막의 표면이미지 관찰과 계면전하이동 특성 연구)

  • Park Sang-Hyun;Lee Dong-Yun;Park Jae-Chul;Kwon Young-Soo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.19 no.3
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    • pp.246-249
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    • 2006
  • We fabricated self-assembled monolayers(SAMs) onto quartz crystal microbalance(QCM) using viologen, which has been widely used as electron acceptor and electron transfer mediator. We determined the time dependence on resonant frequency shift during self-assembly process and observed the morphology of self-assembled monolayers by STM and investigated the electrochemical behavior of SAMs by cyclic voltammetry. Electrochemical deposition of viologen was investigated using electrochemical quartz crystal microbalance(EQCM). The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redok reactions. The total frequency change was about 9.5 Hz, and 7.1 Hz. From the data, we could know the mass change was about 10.16 ng and 7.60 ng, respectively. Finally, the EQCM has been employed to monitor the electrochemically induced adsorption of self-assembled monolayers on Au surfaces.

Self-Assembled and Langmuir-Blodgett Arachidic Acid Monolayers on Silver: A Comparative Reflection-Absorption Fourier Transform Infrared Spectroscopic Study

  • Ahn, Sang-Jung;Mirzakhojaev, Diyas A.;Son, Dong-Hee;Kim, Kwan
    • Bulletin of the Korean Chemical Society
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    • v.15 no.5
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    • pp.369-374
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    • 1994
  • Self-assembled (SA) and Langmuir-Blodgett (LB) monolayers of arachidic acid on silver surfaces have been investigated by a reflection-absorption Fourier transform infrared spectroscopy. Arachidic acid was adsorbed on silver as carboxylate with its two oxygen atoms bound symmetrically to the surface. Although both the SA and LB monolayers consisted of fully extended trans zigzag carbon chains, a closer examination indicated that the SA monotayers should possess a more ordered crystalline structure than the LB monolayers. The infrared spectral data dictated that the extent of methyl group exposure at the air-film interface was greater in the SA monolayers than the LB monolayers, in agreement with the contact angle measurement. From a theoretical analysis, the alkyl chains in each monolayers seemed to be tilted away from the surface normal by less than $3.5^{\circ}$, but in opposite directions. Arachidic acid monolayers were concluded to have same structure as stearic acid monolayers.

Electrochemical Characterization of Nanosized Electrode Arrays Prepared from Nanoporous Self-Assembled Monolayers

  • Choi, Shin-Jung;Park, Su-Moon
    • Bulletin of the Korean Chemical Society
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    • v.23 no.5
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    • pp.699-704
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    • 2002
  • We characterized nanoelectrode arrays prepared from self-assembled monolayers (SAMs) by adsorption from a solution containing thiolated $\beta$-cyclodextrin ($\beta$-CD) and n-alkanethiol on the gold electrode surface, using electrochemical methods. While the framework, the n-hexadecanethiol SAM, effectively blocked electron transfer between the electrode surface and solution-phase redox probe molecules, the $\beta$-CD cavities isolated in the forests of n-hexadecanethiol molecules were shown to act as an ultramicroelectrode array. The shapes of cyclic voltammograms of probe molecules were related to the number densities of $\beta$-CD molecules within the monolayer films. Probe molecules that have the correct combination of physical and chemical characteristics were shown to effectively penetrate the framework through the $\beta$-CD pores and exchange electrons with the electrode surface.

Electrocatalytic Oxidation of NADH at Electrodes of Self-assembled Monolayers Modified with Dopamine (도파민으로 수식된 SAMs 전극에서 NADH의 전기촉매에 의한 산화)

  • Cha, Seong-Keuck
    • Journal of the Korean Chemical Society
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    • v.48 no.2
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    • pp.151-155
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    • 2004
  • The self-assembled mololayers(SAMs)were prepared with cysteine(cys) and subsequently coupled with dopamine(dopa) containing quinone functionality on the gold modified electrodes. The SAMs annealed in ethanol for 6 hours gave a better shaped cyclic voltammogram which had a 0.28 V of formal potential and same redox potential in 0.1M phosphate buffer(pH=7.10). The electrodes were employed to determine concentration of HADH with the result that calibration curve exhibited an excellent correlation(${\geq}$ 0.993) for the concentrations ranging up to 5.0${\times}10^{-4}$ M.