• Archives of Pharmacal Research
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• v.22 no.6
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• pp.608-613
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• 1999

Optimum conditions of chiral derivatization reaction of $\beta$-blockers (acebutolol, arotinolol, betaxolol, bisoprolol, celiprolol, metoprolol and pindolol) with (-)-menthyl chloroformate were investigated for the resolution by HPLC. With more than 30 times molar excess of (-)-methyl chloroformate chiral derivatization reactions were completed within one hour at room temperature except arotinolol and celiprolol. Diastereomeric derivatives of $\beta$-blockers were well resolved on the ODS column using acetonitrile-methanol-water as a mobile phase.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.5
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• pp.474-480
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• 2008

In order to make full color cholesteric displays, color filter-less R, G, B sub-pixel structured cholesteric LC cells have been studied. To make R, G, B colors, UV induced pitch variant chiral dopant was added to cholesteric LC mixtures. The concentration of the photo-sensitive chiral dopant was adjusted so that the initial state showed blue color and the color was changed from blue to green and red with increase of UV irradiation to the cholesteric cells. To prevent the mixing of R, G, B reflective sub-pixel liquid crystals, separation walls were formed using negative photo resister in boundary area between sub-pixels, Through the optimization of the material concentrations and UV irradiation condition, vivid R, G, B colors were achieved.

• Bulletin of the Korean Chemical Society
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• v.22 no.4
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• pp.401-404
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• 2001

A new chiral stationary phase (CSP) based on (1R,2S)-2-amino-1-indanol, which is expected to be conformationally rigid because of its cyclic nature, was prepared. The new CSP was applied in resolving various $N-acyl-\alpha-arylalkylamines$. The chromatographic resolution results on the new CSP were compared with those on the other CSP based on (1S,2R)-norephedrine, which is believed to be conformationally flexible. Comparison of the chromatographic resolution results on the two CSPs demonstrated that conformationally flexible analytes are resolved better on the conformationally rigid CSP while conformationally rigid analytes are resolved better on the conformationally flexible CSP. From these results it was concluded that conformational rigidity or flexibility of CSPs is the important factor for the chiral recognition.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.503-509
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• 2014

The carbon/porous silica composite membrane was fabricated in a simple manner, which could be successfully for the simultaneous separation and production of chiral epoxides and 1,2-diols, based on their differences in hydrophilic/hydrophobic natures. The chiral Co(III)-$BF_3$ salen catalyst adopted in the membrane reactor system has given the very high enantioselectivity and recyclability in hydrolysis of terminal epoxides such as ECH, 1,2-EB, and SO. The optically pure epoxide and the chiral catalyst were collected in the organic phase after hydrolysis reaction. The hydrophilic water-soluble 1,2-diol product hydrolyzed by chiral salen diffused into the aqueous phase through the SBA-16 or NaY/SBA-16 silica composite layer during the reaction. The water acted simultaneously as a reactant and a solvent in the membrane system. One optical isomer was obtained with high purity and yield, and furthermore the catalysts could be recycled without observable loss in their activity in the continuous flow-type membrane reactor.

• Polymer(Korea)
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• v.37 no.3
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• pp.288-293
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• 2013

A group of molecularly imprinted polymers (MIPs) with specific recognition for chiral (S)-ibuprofen were successfully prepared based on hydrogen bonds, utilizing ${\alpha}$-methacrylic acid as a functional monomer. The IR analysis of MIPs showed that the blue- and red-shifted hydrogen bonds were formed between templates and functional monomers in the process of self-assembly imprinting and re-recognition, respectively. According to UV-Vis analysis, we found that the ratio of host-guest complexes between template molecule and functional monomer was 1:1. The effect of cross-linker's quantity on the polymerization was studied by transmission electron microscope (TEM). The adsorption selectivity experiments indicated that MIPs exhibited higher selectivity to (S)-ibuprofen than those to ketoprofen and (R)-ibuprofen, (S)-ibuprofen's structural analogs.

• Archives of Pharmacal Research
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• v.24 no.4
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• pp.281-285
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• 2001

Enantiomers of five racemic ${\beta}_2$-agonists were investigated by capillary electrophoresis employing a hydroxypropyl-${\beta}$-cyclodextrin (HP-${\beta}$-CD). The effects of the concentration of HP-${\beta}$-CD added to the background electrolyte and of the pH of the buffer on the effective mobility and resolution of the studied compounds were examined. Very good resolution was achieved for terbutaline and clenbuterol; salbutamol and bambuterol was able to be partially resolved. Enantioselectivity and resolution were influenced by the concentration of the HP-7-CD, buffer composition and pH.

• Archives of Pharmacal Research
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• v.24 no.2
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• pp.144-149
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• 2001

N-acetylsphingosine (C2-ceramide) is a synthetic water-soluble ceramide mimicking the activity of natural ceramides. By fixing chiral conformation on carbon numbers 2 and 3 in the ceramide structure, four chiral C2-ceramides naming d-erythro-, I-erythro-, d-threo-and 1-three C2-ceramide were synthesized. We have investigated the chiral effects of these C2-ceramides on the sphingolipid metabolism, particularly on both the sphingolipid bio- synthetic pathway and on the degradation pathway. In both HL-60 and U937 cells, the chiral C2-ceramide ($10{\mu}\textrm{m}$) showed sphingosine accumulation monitored fluoromatrically by a high performance liquid chromatographic separation of the sphingoid bases. Most importantly, in HL-60 cells, l-erythro C2-ceramide induced a 50 fold increase in sphingosine as compared to the control, while l-threo C2-ceramide exhibited a minimal 7-fold in-crease. In contrast, sphinganine, another sphingoid base, showed less accumulation by any chiral C2-ceramide tested under the same conditions. These results suggested that chiral C2-ceramide primarilyacts on the sphingolipid degradation pathway rather than on the sphingolipid biosynthetic route. The strong $C_0/G_1$ phase arrest in the cell cycle by treatment of I-erythro C2-ceramide indicates that the blockade of the sphingolipid degradation pathway might be concomitantly involved in the dysfunction of the cell cycle. On the other hand, the fact that all chiral C2-ceramides tested failed to inhibit the activity of sphingosine kinase acting on the removal of sphingosine by producing sphingosine-1 -phosphate demonstrates that chiral C2- ceramides may increase sphingosine by activating various ceramidases by which natural ceramides are divided into sphingosine and free fatty acids. However, the precise steps involved in this interaction are still unknown.

• Bulletin of the Korean Chemical Society
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• v.26 no.5
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• pp.823-825
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• 2005

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.396.3-397
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• 2002

Because of the differences in biological and pharmacological properties between enantiomers of chiral acidic non-steroidal antiinflammatory drugs (NSAIDs) in human body. accurate determinations of their optical purities have been in great need. Racemic ibuprofen. tiaprofen. suprofen. flubiprofen and napoxen were reacted with (1R. 28. 5R)-(－)-menthol to convert them to corresponding diastereomeric (1R. 2S. 5R)-(－ )-menthyl esters. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.161-162
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• 2002

Field of enantioseparations represents one of the actual topics of chemistry. Significant, in some cases dramatic differences in a desired activity as well as in toxic properties of enantiomers of chiral drugs, food additives, agrochemicals, cosmetic products, etc. represents a driving force in this field. The enantiomers of all chiral bioactive compounds have to be isolated and to be tested. Besides the ethical or environmental reasons for developing single enantiomers, it may be a real therapeutic benefit and in some cases, it has been used as a strategy for extending patent life. (omitted)