• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.539-542
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• 1999

The diastereoselectivity in the photocyclization of α-(o-ethylphenyl)acetophenone(1) to 1-methyl-2-phenyl-2-indanol was studied in zeolites X and Y, and compared with that in isotropic solvents. The yields of E-diastereomer at the irradiation of 1 in protic solvents were higher than those in aprotic solvents. The ratios of E-diastereomer to Z-diastereomer in zeolites X and Y were much higher than those in isotropic solvents. The E/Z ratios at the irradiation of 1 in zeolites X were also found to be dependent on the cations present. As the cation size increased from Li+ to Cs+, the ratio decreased. However, any pattern in the E/Z ratios was not found in zeolites Y. The diastereoselectivity observed in the zeolites was interpreted by the conformational restriction imposed by the cavity size. An efficient oxidation of 1 in zeolites RbX and CsX was also observed.

• 한국전기화학회:학술대회논문집
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• 1998.12a
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• pp.153-166
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• 1998

Lithium ion Batteries commercially available since the early nineties in Japan are going to be more and more important for portable electronic devices and even EV applications. Today several companies around the world are working hard to join to market for Lithium secondary batteries. Based on the growing interest for commercial use of batteries also the materials have to be reviewed in order to meet large scale production needs. The requirements especially for electrolytes for lithium batteries are extremely high. The solvents and the lithium salts should be of highest purity. So the supply of these chemicals including packaging, transportation and storage but also the handling in production are critical items in this field. Frolic impurities are very critical for LiPF6 based electrolytes. The influence of water is tremendous. But also the other protic impurities like alcoholes are playing an Important role for the electrolyte quality. The reaction of these species with LiPF6 leads to formation of HF which further reacts with cathode materials (spinel) and anode. To understand the role of the protic impurities more clearly the electrolyte was doped with such compounds and was analyzed for protic impurities and HF. These results which directly show the relation between impurities and quality will be presented and discussed. In addition several investigations on different packaging materials as well as methods to analyze and handle the sensititive material will be addressed. These questions which are only partly discussed in literature so far and never been investigated systematically cover some of the key parameters for understanding of the battery chemicals. This investigation and understanding however is of major importance for scientist and engineers in the field of Lithium ion and Lithium polymer batteries.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.419-424
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• 1987

Kinetic studies on the solvolysis of para-methyl benzyl nitrate and benzyl nitrate were carried out in aqueous methanol, ethanol, acetonitrile, acetone, tetrahydrofuran and dioxane mixtures at 60$^{\circ}$C. The rates were faster in protic solvent mixtures than in aprotic solvent mixtures. This was considered in the light of transition state stabilization by hydrogen bonding solvation of protic solvent mixtures. Grunwald-Winstein equation, extended Grunwald-Winstein equation and correlation between E$_T$(30) and rate constant were applied in order to discuss the transition state variations caused by changing benzyl substituents and solvents. The results showed that strong electrophilic assistance of solvent is operative in the the water-rich solvents.

• Journal of the Korean Chemical Society
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• v.41 no.2
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• pp.63-68
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• 1997

Calorimetric measurements have been carried out for the binary mixture between protic, ROH (R=Me, Et) and dipolar aprotic solvents, MeCN,$Me_2CO,\;MeNO_2(or EtNO_2)$in order to investigate the molecular interaction and liquid structure of isodielectric solvents. From the measured partial molar enthalpies of the solutions, excess enthalpies for the mixing process were determined. The hydrogen bond strength between two components decreases in the order of$ROH-ROH>ROH-Me_2CO>ROH-MeCN>ROH-MeNO_2(or EtNO_2)$and the hydrogen bond donor acidity decreases in the order of MeOH>EtOH. From this result, we can conclude that the most important interaction for the formation of binary liquid mixture comes from the specific hydrogen bond.

• Bulletin of the Korean Chemical Society
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• v.19 no.9
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• pp.980-985
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• 1998

The excited-state intramolecular proton transfer (ESIPT) emission has been observed for 0.01 mM p-aminosalicylic acid (AS) in nonpolar aprotic solvents as demonstrated by the large Stokes' shifted fluorescence emission around 440 nm in addition to the normal emission at 330 nm. However in aprotic polar solvent such as acetonitrile, the large Stokes' shifted emission band becomes broadened, indicating existence of another emission band originated from intramolecular charge transfer (ICT). It is noteworthy that in protic solvents such as methanol and ethanol the normal and ICT emissions are quenched as the AS concentration decreases, followed by the appearance of new emission at 380 nm. These results are interpreted in terms of ESIPT coupled charge transfer in AS. Being consistent with these steady-state spectroscopic results, the picosecond time-resolved fluorescence study unravelled the decay dynamics of the ESIPT and ICT state ca. 300 ps and ca. 150 ps, respectively with ca. 40 ps for the relaxation time to form the ICT state.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.333-333
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• 2013

The poor conductivity of poly (3,4-ethylene dioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) film hinders to use for a flexible electrode in solar cells. In this report we demonstrate that the conductivity of PEDOT:PSS film can be enhanced by modifying structures in a mixture of PEDOT: PSS aqueous solution and various organic solvents such as polar protic (2-propanol, methanol, ethanol, formic acid) and aprotic solvents (acetone and acetonitrile). To comparatively study the structural effects on the resulted electrical properties, the films are spin-coated on glasses and ITO. At the same time, a contact angle goniometer is used for clarifying a mechanism of wettability of PEDOT (hydrophobic) and PSS (hydrophilic) on the observed conductivity. The structures and electrical properties are investigated by FE-SEM (Field Emission Scanning Electron Microscopy), AFM (Atomic Force Microscopy), and 4-point probe, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.21 no.2
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• pp.49-56
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• 1995

Chitosan microcapsules and microbeads were prepared by W/O emulsion method, and their morphologies were observed through SEM. The microcapsules have skin layer of 8 Um and 250 Um of mean diameter, The swelling test showed higher s welling ability in protic solvents than in aphotic solvents. After containing moth-yl violet in the microcapsules, the release patterns were investigated. The results sho wed that the addition of Iysozyme in pH 5.1 acetate buffer accelerated the re-lease rate. In case of the microbeads, the mean diameter was about 70 Um. The surface of the microbeads showed porous structures. The swelling ability of the beads revealed two times higher than the one of the microcapsules.

• Mass Spectrometry Letters
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• v.8 no.2
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• pp.29-33
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• 2017

Understanding the mechanisms that control and concentrate the observed electrospray ionisation (ESI) response from peptides is important. Controlling these mechanisms can improve signal-to-noise ratio in the mass spectrum, and enhances the generation of intact ions, and thus, improves the detection of peptides when analysing mixtures. The effects of different mixtures of aqueous: organic solvents (25, 50, 75%; v/v): formic acid solution (at pH 3.26) compositions on the ESI response and charge-state distribution (CSD) during mass spectrometry (MS) were determined in a group of biologically active peptides (molecular wt range 1.3 - 3.3 kDa). The ESI response is dependent on type of organic solvent in the mobile phase mixture and therefore, solvent choice affects optimal ion intensities. As expected, intact peptide ions gave a more intense ESI signal in polar protic solvent mixtures than in the low polarity solvent. However, for four out of the five analysed peptides, neither the ESI response nor the CSD were affected by the volatility of the solvent mixture. Therefore, in solvent mixtures, as the composition changes during the evaporation processes, the $pK_b$ of the amino acid composition is a better predictor of multiple charging of the peptides.

• Bulletin of the Korean Chemical Society
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• v.32 no.2
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• pp.664-672
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• 2011

A series of hydrophilic chromophores was synthesized through introduction of dendritic sulfonate anions using click chemistry. A dendron structure bearing several sulfonate groups enhances hydrophilicity of attached chromophores. A click triazole formation connects chromophores with hydrophilic groups. A neutral trichloroethyl sulfonate has versatile features such as easy introduction, chemical endurance for isolation or storage, and convenient transformation to a hydrophilic anion. Zinc and OH mediated cleavage of trichloroethyl group from the neutral sulfonate undergoes to generate a water-soluble sulfonate anion. The solubility was examined with different counter cations and in different pH media and thus increased with the number of attached sulfonate ion. Two hydrophilic chromophores of stilbene-derived and azobenzene-derived dipolar structures exhibit clear negative and positive solvatochromism in protic solvents, respectively.

• Journal of the Korean Chemical Society
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• v.17 no.6
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• pp.434-438
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• 1973

Distribution coefficients (C) of some transition metal ions such as Ni(II), Cu(II), Cd(II), Zn(II), and Hg(II) have been determined in methanol-, ethanol-, isopropanol-, acetone-, and dimethylsulfoxide-water mixtures by using Rexyn 101 (Na-form) resin and 0.2 M sodium chloride solution. The log C values of the metallic ions decrease almost straightly with the increase in reciprocal values of the dielectric constants of the mixed solvents. In the solvents having the same dielectric constants, the distribution coefficients of the metallic ions decrease with the increase in the basicity of the aprotic organic molecule and with the decrease in the molecular size of the protic organic molecule. The separation of the metallic ions has been accomplished with the eluting agent suggested by the C values.