• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.197-197
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• 2011

In this study, in contrast with cases in which Scanning Tunneling Microscopy (STM) tip-induced reactions were instigated by the tunneling electrons, the local electric field, or the mechanical force between a tip and a surface, we found that the tungsten oxide (WO3) covered tungsten (W) tip of a STM acted as a chemical catalyst for the S-H dissociative adsorption of phenylthiol and 1-octanethiol onto a Ge(100) surface. By varying the distance between the tip and the surface, the degree of the tip-catalyzed adsorption could be controlled. We have found that the thiol head-group is the critical functional group for this catalysis and the catalytic material is the WO3 layer of the tip. After removing the WO3 layer by field emission treatment, the catalytic activity of the tip has been lost. 3-mercapto isobutyric acid is a chiral bi-functional molecule which has two functional groups, carboxylic acid group and thiol group, at each end. 3-Mercapto Isobutyric Acid adsorbs at Ge(100) surface only through carboxylic acid group at room temperature and this adsorption was enhanced by the tunneling electrons between a STM tip and the surface. Using this enhancement, it is possible to make thiol group-terminated surface where we desire. On the other hand, surprisingly, the WO3 covered W tip of STM was found to act as a chemical catalyst to catalyze the adsorption of 3-mercapto isobutyric acid through thiol group at Ge(100) surface. Using this catalysis, it is possible to make carboxylic acid group-terminated surface where we want. This functional group-selective adsorption of bi-functional molecule using the catalysis may be used in positive lithographic methods to produce semiconductor substrate which is terminated by desired functional groups.

• Archives of Pharmacal Research
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• v.11 no.4
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• pp.285-291
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• 1988

2-mercaptoethanol, thioglycolic acid, glutathione, 3-mercapto-1, 2-propanediol and 3-mercapto-2-butanol showed catalytic activities on the hydrolysis of $\alpha$-amino-phenylacetonitrile to phenylglycineamide at the rate of 12.19 $\times$ $10^{-2}$, 8.03 $\times$ $10^[-2}$, 6.83 $\times$ $10^{-2}$, 8.60 $\times$ $10^{-2}$ and 6.04 $\times$ $10^{-2}$ mM $min^{-1}$, respectively. hte hydrolysis rate was faster in buffer than in water. The hydrolysis of the nitrile compound to phenylglycine was limited.

• Current Research on Agriculture and Life Sciences
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• v.5
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• pp.168-172
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• 1987

Methods were developed to synthesize optically active mercaptoglycerol from optically active isopropylidene glycerols. 1,2-Isopropylideneglycerol was tosylated and the tosyl group displaced with thiolacetate. Base hydrolysis and oxidation gave 1,1'-dithiobis-2,3-isopropylidene-2,3-propanediol. This compound could be used as a source of mercaptoglycerol, or reacted with 1-decenyl lithium to form cis-1-S-dec-1'enyl-2,3-isopropylidene-1-mercapto-2,3-propanediol. The latter is a stereospecific synthetic route to cis-alkenyl thioethers of protected mercaptoglycerol, and it may be useful for the preparation of a thioplasmalogen substrate for plasmalogenase.

• Polymer(Korea)
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• v.29 no.4
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• pp.331-337
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• 2005

In general, alkanethiolates having carboxylic acid in the tail group have been used as biorecepton. In this study, we have immobilized a cytochrome c protein using conjugated aromaticthiolates in order to improve the electrical property and physical stability of alkanethilolates. The pattern formation of self-assembled aromaticthiolate monolayers was as follow. Aromatic thiolates bound on the gold surface by the adsorption of 4'-mercapto-biphenyl-4-carboxylic acid and 4-mercapto-[1,1';4',1']terphenyl-4'-carboxylic acid were oxidized by the irradiation of deep UV light through a negative mask. The negative type pattern of the self-assembled monolayer (SAM) was obtained by developing with a deionized water. The pattern formation and electrical conductivity of aromaticthiolate SAMs was investigated by the measurements of STM and AFM. In addition, cytochrome c or ferrocene amide was immobilized onto the patterned substrate. We also studied on the effect of conjugated aromatic thiolates on the electrical activity of cytochrome c or ferrocene amide by cyclic voltammetry.

• Journal of the Korean Chemical Society
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• v.30 no.5
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• pp.475-482
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• 1986

Rates and equilibriurn of complex formation between $Ni^{2+}$ and D-penicillamine have been investigated in aqueous solutions. Kinetic study on the complex formation were performed in the pH range of 8∼9 by the use of pressure-jump technique. D-Penicillamine coordinates to the nickel(II) ion utilizing sulfur and nitrogen as donor atoms in the high pH condition (pH 9.2). However, in the pH range of 8.25∼9.07, the stepwise stability constant becomes drastically reduced and the undissociated mercapto group does not participate in bonding. The rate-determining step of the complexation reaction is found to be the release of a water molecule from the inner-coordination sphere of $Ni^{2+}$ ion.

• Journal of the Korean Chemical Society
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• v.47 no.5
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• pp.439-446
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• 2003

Surface-enhanced Raman(SER) spectroscopy was utilized to investigate the adorption orientation of the 4-biphenylcarboxylic acid(BPCA) derivatives, such as 4'-cyano-BPCA(c-BPCA), 4'-mercapto-BPCA(m-BPCA), and 4'-amino-BPCA(a-BPCA), which were adsorbed on Au and Ag colloid monolayers. For the systematic approach, information regarding the adsorption behavior of benzoic acid, biphenyl, and BPCA was applied to the target molecules. From the spectral behaviors of benzene ring, C-H stretching, carboxylate anion, and the other finger printing vibrational modes, it was concluded that only the m-BPCA was adsorbed tilt with thiol group being adsorbed on Au surface, whereas the other molecules were adsorbed flat on both Au and Ag surfaces.

• Polymer(Korea)
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• v.26 no.4
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• pp.445-451
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• 2002

In this work, the adsorption characteristics and mechanical interfacial properties of treated silicas by silane coupling agents, such as, ${\gamma}$-methacryloxy propyl trimethoxy silane (MPS), ${\gamma}$-glycidoxy propyl trimethoxy silane (GPS), and ${\gamma}$-mercapto propyl trimethoxy silane (MCPS), were investigated. The equilibrium spreading pressure ($pi_e$), surface free energy ($gamma_s$ s/), and specific surface area ($S_{BET}$) were studied by the BET method with $N_2$/77 K adsorption. The developments of nonpolar functional groups of the silica surfaces treated by silane coupling agents led to the increase in the $S_{BET}$, $pi_e$, and $gamma_s$, resulting in the improved tearing energy ($G_{mc}$)of the silica/rubber composites. The composites treated by MPS showed the superior mechanical interfacial properties in these systems. These results explained by changing of crystalline size, dispersion, agglomerate, and surface functional group of silica/rubber composites.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2979-2984
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• 2014

Silver nanoparticles have been synthesized by liquid-phase and alcohol reduction methods. Silver-doped silica-complex nanoparticles were prepared using a sol-gel process. The formation, structure, morphology, and particle size of the nanoparticles have been studied using several techniques. Silver nanoparticles of size of 30-40 nm were formed successfully by alcohol reduction. TEM images show that both the concentration and the molecular weight of polyvinyl pyrrolidone (PVP) considerably affect the size of the emerging silver nanoparticles. The number of silver-doped silica-complex particles increased by a mercapto-group treatment that showed a narrower size distribution than that of silica treated with amino groups. The silver/polyester and silver-doped silica/polyester masterbatch chips showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli.

• YAKHAK HOEJI
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• v.47 no.6
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• pp.450-455
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• 2003

Synthesis of (lR,5S,6S)-6-[(lR)-1-hydroxyethyl] -2-[(3S,5S)-5-(2-ethoxycarbonyl-1-moxy(hydroxy)iminoethyl)pyrrolidine-3-ylthio]-1-methylcarbapen-2-em-3-carboxylic acids (10a,l0b) were described. Methyl(2S,4S)-4-tritylthio-1-(allyloxycarbonyl)pyrrolidine-2-carboxyla late (I) was prepared from trans-4-hydroxy-L-proline with (2S,4R)-abs olute configuration as starting material. (2S,4S)-1-allyloxycarbonyl-2-(2-ethoxycarbonyl-hydroxy(methoxy )iminoethyl)-4-mercapto- pyrrolidines (6,7) were obtained from the tritylthio compound (I). (lR,5S,6S)-6-[(lR)-1-hydroxyethyl]-2-[(3S,5S)-5-(2-ethoxycarbonyl-1-methoxy(hydroxy)imino-ethyl)pyrrolidine-3-ylthio]-1-methylcarbapem-2-em-3-carboxylic acids (10a,10b) were obtained by the coupling reaction with carbapenem diphenylphosphates (8) and pyrrolidine-thiol moiety (6,7). Their in vitro antibacterial activities against both Gram-positive and Gram-negative were tested. Compounds ( 10a,10b) showed potent antibacterial activity except pseudomonas aerusinosa.

• YAKHAK HOEJI
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• v.40 no.5
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• pp.550-557
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• 1996

One of therapeutics in liver disease (morbus wilson) is D-penicillamin (D-pen: D-3-mercapto-valin). Especially the cross-linking of collagen molecules could be inhibited by D-pe n in extracellular space. In this study we investigated the antifibrotic effects of D-pen in rats that were induced the liver fibrosis by bile duct ligation and scission (BDL/S). Rats were treated for 4 weeks with D-pen after BDL/S operation or sham operation. The balance between fibrogenesis-marker (PNIIIP) and the fibrolysis-maker (PNIVP) were observed in sera by RIA (radioimmunoassay), and the parameter of collagen deposition in liver tissue (hydroxyproline: HYP) was measured by colorimetry. The weight of liver in BDL/S operated group was increased significantly in compared with sham operation group (15.2g${\pm}$1.1, vs 11.9g${\pm}$3.9: p<0.005, p<0.05). The rats group treated by D-pen showed the lower level of PNIIIP (6.7ng/ml${\pm}$1.5, vs 9.5ng/ml${\pm}$2.8) and the higher value of PIVCP (14.0ng/ml${\pm}$1.9, vs 7.9ng/ml${\pm}$1.5) in sera that compared to untreated rats. The content of HYP was decreased by 141% in BDL/S with D-pen treated group than that of it in BDL/S group. No correlation was revealed between collagen parameters in sera and HYP in liver tissue of BDL/S operated and D-pen treated rats. The group treated with D-pen showed the lower value of clinical biochemistry parameters (GOT: glutamate oxalacetate transaminase, Total-Bilirubin) in compared with only BDL/S operated rats, but the value of GPT (glutamate pyruvate transaminase) and Alkaline phosphatase in two BDL/S groups was nearly same. In the histological finding, we observed mild bile duct proliferation, weak inflammation and fibrosis in BDL/S with D-pen treated group, but BDL/S operated group showed the formation of septum (island of hepatocytes), massive bile duct proliferation. This result represents that the BDL/S operation induces liver fibrosis (cirrhosis) in 4 weeks, and D-pen inhibits the synthesis of collagen weakly and stimulates the degradation of collagen in the extracellular space. We conclude that the monitoring of PNIIIP, PIVCP in sera is useful parameter for screening of antifibrotic effect, and D-pen delay the liver fibrosis.