• Journal of the Korean Chemical Society
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• v.64 no.2
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• pp.74-78
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• 2020

A push-pull conjugated dye (DCMP) was covalently immobilized on a silanized glass surface to produce a high sensitivity pH sensor film for operating in the acidic region. A pH-sensitive sensor film was prepared by photo-initiating copolymerization of a modified DCMP (DCMA), 2-hydroxyethyl methacrylate (HEMA) and triethylene glycol dimethacrylate on the silanized glass surface. The absorbance of the sensor film increased with increasing pH between pH 2.0 and 5.0, and the fluorescence intensity of the film also increased about 50 times with increasing pH in the same pH range. The sensor film was reversible and reproducible under acidic conditions. The sensor film showed a relatively short response time between 20-50 seconds and high selectivity for proton in the presence of various metal ions.

• Journal of the Korean Chemical Society
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• v.43 no.1
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• pp.7-119
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• 1999

• Bulletin of the Korean Chemical Society
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• v.26 no.7
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• pp.1029-1030
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• 2005

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1329-1332
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• 2012

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.600-603
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• 1997

Spherical, submicrometer particles of barium-titanyl oxalate were homogeneously precipitated by thermal decomposition of diethyl oxalate in acidic aqueous solutions. The rates of oxalate ion generations, determined by various combinations of temperature and initial concentration of diethyl oxalate had a very important effect on the particle size distribution. Monosized, bimodal, or broad unimodal powders were obtained under certain combinations of experimental variables.

• Journal of the Korean institute of surface engineering
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• v.49 no.3
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• pp.231-237
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• 2016

This article reports a new chemical bath for preparing a mirror-like surface of AZ31 Mg alloy. In order to find an appropriate chemical polishing solution, four different acidic solutions of sulphuric acid, nitric acid, acetic acid and a specially designed mixture of nitric acid and acetic acid were investigated in view of the changes in surface appearance, roughness and dissolution rate of AZ31 Mg alloy. The surface scales on AZ31 Mg alloy were readily removed by all the acidic solutions, but a reflective surface was produced only by etching in the specially designed solution, and only after a specific etching time. The surface roughness increased with etching time in sulphuric acid, nitric acid, and acetic acid, but it lowered after a specific etching time in the specially designed mixture of nitric acid and acetic acid. Dissolution rate of the alloy in the specially designed mixture of nitric acid and acetic acid appeared to be more than twice than that in separate nitric acid or acetic acid. In this work, we recommend the mirror-like surface of AZ31 Mg alloy obtained by polishing for an optimum time in a mixture of nitric acid and acetic acid for following surface finishings, chemical conversion coating, electroplating, electrophoretic painting and anodizing treatment.

• Journal of the Korean Chemical Society
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• v.19 no.6
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• pp.434-437
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• 1975

By fractional crystallization D-mandelic acid salt of diethyl-dl-1-aminobenzylphosphonate prepared from benzaldehyde, diethylphosphite and ammonia at the atmospheric pressure, gave diethyl(-)-1-aminobenzylphosphonate. (+)-1-Aminobenzylphosphonic acid was obtained by acidic hydrolysis of diethyl(-)-1-aminobenzylphosphonate hydrochloride.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1635-1639
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• 2011

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]$Sb_nF_{5n+1}$ (n ${\geq}$ 2; bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT$^{y+}$][SbF$_6^-$]$_y$ (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

• Journal of the Korean Chemical Society
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• v.7 no.4
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• pp.225-229
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• 1963

The nature of the two isomers of 4-nitroazoxybenzenes in strongly acidic solution have been analyzed by U.V. spectrophotometry. Oxygen atom in the azoxy-group of $\alpha$-and $\beta$-4-nitroazoxybenzene in strong acid solution migrates neither to para position nor ortho position of the unsubstituted benzene ring of the compound in contrast with the cases of methyl-and bromo-substituted azoxybenzene, and shown no Wallach rearrangement. Since the $^1A{\rightarrow}^1H$ bands of the spectra shown hyperchromic effect whereas the ${\pi}{\rightarrow}{\pi}^*$ bands of them exhibit extream hypochromic effect, it appears most likely that trans ${\rightarrow}$cis isomerization take place in the media. A mechanism of a triangular transition state by which the transformation might be proceeded, is proposed.

• Journal of the Korean Chemical Society
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• v.6 no.2
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• pp.162-170
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• 1962

The rearrangement reaction of azoxybenzenes into hydroxyazobenzenes in strongly acidic solution has been studied by an U. V. spectrophotometric method and by isolation of the rearranged compound. In all cases under investigation, it appeared that the oxygen atom in the azoxy group migrated to the unsubstituted ring, depending neither on the substituent already present in the other ring, nor on the distance between the oxygen atom and the eligible position; whereas, the position in the open ring, ortho or para, to which the oxygen migrates depends on the substituent already present in the other ring. In all compounds besides ${\alpha}$-and ${\beta}$-4-methyl azoxybenzene, the oxygen atom migrates to the para position. In the case of ${\alpha}$ and ${\beta}$-4-methylazoxybenzene, the oxygen atom migrates to the ortho position of the unsubstituted ring.