• Bulletin of the Korean Chemical Society
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• v.32 no.6
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• pp.2058-2062
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• 2011

The effect of the addition of ionic liquids with four different cations (imidazolium, pyrrolidinium, piperidinium and pyridinium) on the performance of dye-sensitized $TiO_2$ solar cells based on electrolytes containing a t-butylpyridine (TBP) in 3-methoxypropionitrile (MPN) was studied. A total of 18 ionic liquids with mono-, di- and tri-alkyl derivatives were used in the present study, and among them a pyridinium cation with a mono-alkyl group showed better cell efficiency than the others. The best photoelectric conversion efficiency, 7.213%, was obtained using 1-hexylpyridinium iodide with an open-circuit photovoltage ($V_{oc}$) = 0.731 V, a short-circuit photocurrent density ($J_{sc}$) = 16.175 $mA/cm^2$, and a fill factor (ff) = 0.610 under AM1.5 and 100 $mW/cm^2$ illumination.

• KSBB Journal
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• v.32 no.2
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• pp.103-107
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• 2017

The effect of the trehalose incorporation on the biological membranes was investigated with respect to the phase of the membranes using the fluorescence intensity change. Spherical phospholipid bilayers, vesicles, were prepared only with the variation in the phase of each layer via a double emulsion technique. In the aqueous inside of the vesicles, 8-Aminonaphthalene-1,3,6-trisulfonic acid disodium salt(ANTS) was encapsulated. As a quencher, p-Xylene-bis(N-pyridinium bromide)(DPX) was included in the buffer where the vesicles were dispersed. The fluorescence scale was calibrated with the fluorescence of ANTS vesicles in p-Xylene-bis(N-pyridinium bromide)(DPX)-included-buffer taken as 100% fluorescence and the mixture of ANTS and DPX in the buffer as 0% fluorescence. Trehalose injection into the vesicle solution led the distortion of the membrane. It was found that the distortion was related to the phase of each layer the vesicle up on the ratio of trehalose to lipid. In the identical measurements at glucose, the behavior of the distortion was completely different from that of trehalose. These results seem to depend on the stability of the vesicles, due to the osmotic and volumetric effects on the headgroup packing disruption.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.621-624
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• 1996

Betaine was treated with hydrochloric acid and then with sodium borohydride to give a hydroxy compound 2. The reaction of 2 with thionyl chloride followed by thiourea led a comp ound 5. Oxidation of compound 2 with pyridinium dichromate(PDC) and succesive treatment with Lawesson's reagent also afforded the same compound 5. Cleavage of N-C14 bond compound of 7 was carried out via two reaction sequence from the compound 4. Finally, compound 10 was sythesized by a series of transformations from the compound 4.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.3
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• pp.475-479
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• 1997

A decrease in the circulating levels of estrogen, occuring as a consequence of post menopausal decline or from surgical ovariectomy, results in an accelerated loss of bone. Estrogen has been shown to stimulate lysyl oxidase activity, and the treatment with estrogen increased the pyridinium content of cortical bone. a trivalent mature cross-links collagen fibrils named pyridinoline, which is especially abundant in collagen of cartilage and bone, markedly increases with growth in humans and rats. The main aim of this study was to examine the increased bone loss caused by ovariectomy through monitoring the concentrations of the collagen and the pyridinium cross-links of collagen, pyridinoline. The ovariectomized rats, 4 weeks old, were divided at random into two or three groups of 5. Ovariectomies were carried out on both of the saline-treated group(OVX(NH)) and the estrogen-treated group(OVX(H)) using the dorsal approach and sham operations were performed on the sham-operated group(sham). They were maintained under identical conditions for 4 or 8 weeks and were allowed free access to food and water. it was observed that there was no significant difference between the control group and the sham-operated group, however, the control group had a higher content of collagen than the saline-treated group after 4 weeks and 8 weeks. Based on these results, iot is supposed that estrogen can enhance collagen synthesis and affects the pyridinoline formation in collagen fibrils through stimulating lysyl oxidase activity.

• Journal of the Korean Chemical Society
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• v.18 no.6
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• pp.437-442
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• 1974

Pentacyclo ($5,3,0,0^{2,5},06{3,9},0^{4,8})-decane-6,10-dione was synthesized from the cyclopentanone in good overall yield(60%). Cyclopentanone ethylene ketal(Ⅰ) was brominated with pyridinium bromide perbromide, and the brominated ketal(Ⅱ) was converted to the dimer of cyclopentadienone ethylene ketal(Ⅲ). The ethylene ketal(Ⅲ) was again converted to the dicyclopentadiene-1,8-dione(Ⅳ). Finally, the pentacyclo ($5,3,0,0^{2,5},06{3,9},0^{4,8})-decane-6,10-dione(Ⅴ) was synthesized from the dicyclopentadilene-1,8-dione(Ⅳ) by photochemical cyclization.

• Bulletin of the Korean Chemical Society
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• v.4 no.3
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• pp.115-119
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• 1983

The ionic association constants (K) of 2, N-dimethyl pyridinium iodide (2NDMPI) in 95 volume percentage ethanol-water mixture were determined by a modified UV and conductance method at $20^{\circ}C{\sim}50^{\circ}C$ under 1 to 2000 bars. The K values increase with increasing pressure and decrease with temperature. The total partial molar volume change (${\Delta}V$) has relatively small negative value and the absolute ${\Delta}V$ value decrease with increasing pressure and temperature. The ion size (a) and solvation number (n) of 2NDMPI were about 5 $\AA$ and changed from 1 to 3 with decreasing temperature. Other thermodynamic parameters such as enthalpy (${\Delta}H^{\circ}$) and entropy (${\Delta}S^{\circ}$) for the equilibrium of the 2NDMPI were evaluated. From all the parameters mentioned above, we came to conclusion that the electrostriction effect of 2NDMPI in the ethanol-water mixture is enhanced with increasing pressure and decreasing temperature.

• Bulletin of the Korean Chemical Society
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• v.8 no.3
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• pp.168-170
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• 1987

The reaction between 1-benzyl-3-carbamoyl-1,4-dihydropyridine (BNAH) 1 and various 1-arylpyridinium salts 2, and the reaction between 1-(4-methylphenyl)-1,4-dihydropyridine 4b and 1-aryl-3-carbamoylpyridinium (1-arylnicotinamide) salts 5 were carried out. The extents of reaction in equilibrium were estimated by nmr integration data. The equilibrium constants for the reactions, K, and the standard Gibbs free energy changes for the reduction of the pyridinium salts to the corresponding 1,4-dihydropyridines ${\Delta}G^{\circ}'$ were evaluated. The Hammett plot of log K for the reaction between 1 and 2, and ${\Delta}G^{\circ}'$ against ${\sigma}_p$ of the substituents in 1-aryl moiety shows linear correlation with the reaction constant ${\rho}$ of 9.4 (for log K vs ${\sigma}_p$) and -54.5 KJ/mole (for ${\Delta}G^{\circ}'$ vs ${\sigma}_p$). It was found that 1-aryl-1,4-dihydropyridines have much higher reducing power than the corresponding 1-aryl-1,4-dihydronicotinamides, and the power is affected greatly by the electron-withdrawing ability of the substituents in aryl group. The reactions were utilized for preparation of 1,4-dihydropyridines bearing highly electron-withdrawing groups such as 4-nitrophenyl and 2,4-dinitrophenyl, which could not be obtained by conventional dithionite reduction of the corresponding pyridinium salts due to the base-labile nature of the salts.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.79-85
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• 1984

The ionic association constant(K) of 2,4,6, N-tetramethyl pyridinium iodide (TeMPI) in 95 volume percentage ethanol-water mixture were determined by a modified UV and conductance method at $25^{\circ}C$ to $50^{\circ}C$ under 1 to 2,000 bars. The K values increase with increasing pressure and have maximum value at $40^{\circ}C$. The partial molar volume hange (${\Delta}V$) has relatively small negative value and the absolute values of ${\Delta}$ are minimum at $40^{\circ}C$. The ion size parameter(a) of TeMPI have maximum value at $40^{\circ}C$. {\Delta}H^{\circ}$ values are zero, positive and negative at 40^{\circ}C$, $25^{\circ}C$ and $50^{\circ}C$ respectively. Other thermodynamic parameters such as the changes of standard entropy ({\Delta}S^{\circ}$) and free energy {\Delta}G^{\circ}$ were evaluated. From these experimental results, we came to conclusion that TeMPI is stabilized by the elevation of pressure and that of temperature below $40^{\circ}C$ but weakly dimerized at $40^{\circ}C$ because of the intermolecular hydrophobic interaction of eight methyl groups of two molecules. And it thermally decomposed above $50^{\circ}C$.

• Journal of the Korean Chemical Society
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• v.54 no.3
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• pp.261-268
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• 2010

In this account, three synthetic methodologies that serve as the basis for new strategies for the preparation of selected natural products are briefly introduced. One process, involving ruthenium carbene catalyzed ring rearrangement metathesis developed by Grubbs and his coworkers, transforms alkene-tethered cycloalkenes to thermodynamically more favored alkene-tethered cycloalkenes. Another ruthenium carbene promoted reaction, referred to as dienyne metathesis, was uncovered in early studies by Grubbs and his collaborators. This process converts dienynes to fused bicyclic conjugated dienes. Finally, a novel photo-electrocyclization reaction of pyridinium salts, which leads to the formation of 4-aminocyclopenten-3,5-diol derivatives, is discussed. Examples are provided to show the utility of these methodologies in natural product synthesis. Emphasis is given to studies in which pyridinium salt photochemistry is coupled with ring rearrangement and dienyne metathesis in routes for the synthesis of polyhydroxyalted indolizidine alkaloids and the construction of the tricyclic core of the lepadiformine and cylindricine alkaloids.

• Journal of the Korean Graphic Arts Communication Society
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• v.12 no.1
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• pp.133-143
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• 1994

A new photochromic spiroxazine dye having a pyridinium s-triazine moiety has been prepared. It shows a reversible photochemical color change from colorless to reddish-purple in ethanol solution. In ethanol solution the half life time of the open form was 150sec, which was shortened by raising temperature. Silica-immobilized spiroxazine(6). Fine power of silica-immobilized spiroxazine was changed intensely blue from colorless by U.V. light or sunlight.