• Polymer Science and Technology
• /
• v.13 no.5
• /
• pp.686-693
• /
• 2002

• Korean Journal of Materials Research
• /
• v.4 no.6
• /
• pp.695-703
• /
• 1994

Some 4-(4-alkyloxybenzoyloxy)-4'-(S)-$\alpha$-chloro-alkanoyloxybiphenyls have been synthesized and their mesomorphic properties were studied. They show a ferroelectric chiral smectic C phase in addition to the chiral nematic and smectic A phase. We obtained a large spontaneous polarization exceeding $10^{-7}\textrm{cm}^2$ in new biphenyl ester series.

• Journal of the Korean Chemical Society
• /
• v.47 no.6
• /
• pp.597-600
• /
• 2003

Cinchona alkaloids (1-4) were used as chiral ligands for the enantioselective Reformatsky reactions. The order of addition of the Reformatsky reagent to ligands was the important factors for the chiral induction. The ratio of Reformatsky reagent to ligand and aldehyde was also effected on the reaction yields.

• Journal of the Korean Chemical Society
• /
• v.42 no.6
• /
• pp.733-739
• /
• 1998

• Applied Chemistry for Engineering
• /
• v.18 no.3
• /
• pp.218-226
• /
• 2007

The stereoselective synthesis of chiral terminal epoxides is of immense academic and industrial interest due to their utility as versatile starting materials as well as chiral intermediates. In this study, new dinuclear chiral Co (salen) complexes bearing gallium-, indium- and tallium-chloride have been synthesized and characterized. The mass and EXAFS spectra provided the direct evidence of formation of dinuclear complex. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides having ether or ester groups by hydrolytic kinetic resolution technology. The easily prepared dimeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ nucleophile, providing enantiomerically enriched terminal epoxides (> 99% ee). The dimeric structured chiral salen showed remarkably enhanced reactivity and may be employed substantially lower loadings than its monomeric analogues. The system described in this work is very efficient for the synthesis of chiral epoxide and 1,2-diol intermediates

• Korean Chemical Engineering Research
• /
• v.48 no.5
• /
• pp.574-582
• /
• 2010

In this study, the possibility of a quartz crystal micro-balance(QCM) modification of crystallization of L-Penicillamine and D-Penicillamine with a Vapor Diffused Molecular Assembly Technique and its application to the R-(-)-Mandelic acid and S-(+)- Mandelic acid measurement was investigated. The 3-dimensional structures of L-Penicillamine and D-Penicillamine on the surface of QCM were verified to be different from each other through QCM and AFM analyses. The D-Penicillamine modified QCM had specific recognition to the R-(-)-Mandelic acid, but L-Penicillamine modified QCM had no specificity to the R-(-)-Mandelic acid and S-(+)- Mandelic acid. From these results, it was known that the QCM could be modified with various selective meterials via VDMA, and the chiral isomer such as a Mandelic acid isomer could be detected by using a modified QCM.

• Applied Chemistry for Engineering
• /
• v.18 no.6
• /
• pp.562-567
• /
• 2007

The stereoselective synthesis of chiral terminal epoxide is of immense academic and industrial interest due to their use as versatile starting materials as well as chiral intermediates. In this study, new polymeric chiral Co(salen) complexes bearing tallium (III)chloride and iron (III)chloride (ferric chloride) have been synthesized and characterized. Their catalytic activity and selectivity have been demonstrated for the asymmetric ring opening of various terminal epoxides using water and phenol derivatives as nucleophiles. The easily prepared polymeric complexes exhibited very high enantioselectivity for the asymmetric ring opening of epoxides with $H_2O$ and phenol nucleophiles, providing enantiomerically enriched terminal epoxides (> 98% ee). The system described in this work is very efficient for the synthesis of chiral epoxide, 1,2-diol and ${\alpha}$-aryloxy alcohol intermediates.

• Journal of the Korean Chemical Society
• /
• v.46 no.5
• /
• pp.412-429
• /
• 2002

Chiral separation of gemifloxacin, an quinolone antibacterial agent, using (+)-(18-crown-6)-tetracar-boxylic acid $(18C6H_4)$ as a chiral selector was performed by capillary electrophoresis (CE). Direct analysis of quinolone antibacterial agent in body fluid is beneficial in terms of fast analysis time, multicomponent analysis. However, high con-centration of sodium ion in body fluid can prevent gemifloxacin from interacting with $18C6H_4$ since sodium ion has high affinity with $18C6H_4$ due to the strong charge interaction. Ethylenediaminetetraacetic acid (EDTA), as a chelating ligand, was added in the running buffer in order to reduce the interaction between sodium ion and the chiral selector. Increased separation efficiency and reduced migration time were observed while sodium ion exists in the sample solution at the concentration up to 150 mM.

• Journal of the Korean Chemical Society
• /
• v.39 no.4
• /
• pp.257-265
• /
• 1995

Free amino acids were isolated from milk and their absolute amounts were determined by reversed phase high performance liquid chromatography after derivatization with dansyl chloride. The determination of D- and L-amino acids was based on achiral separation on a C18 column. It was found that milk contained totally 41.00 mg DL-amino acids in 100 mL milk. The level of D-amino acids to L-amino acids was determined by a column-switching system combining an achiral reversed phase separation and chiral chelate additive. The chiral separation was carried out with addition of the chiral Cu(N-benzyl-L-proline)2 chelate to the mobile phase in reversed phase liquid chromatography. It was found that the determination of 16 different amino acids is feasible in the milk sample with a C18 column separation and 12 D-amino acids out of the 16 amino acids can be determined via the column-switching system with chiral separation. 2.05% of D-glutamic acid and 2.93% of D-alanine were found in milk.

• KSBB Journal
• /
• v.18 no.4
• /
• pp.261-265
• /
• 2003

Ibuprofen was analyzed by chiral high performance liquid chromatography. Retention behaviours of the standard mixtures of ibuprofen were investigated to obtain their acceptable resolution. A chromatographic column (3.9 ${\times}$ 300 mm) was packed by Kromasil CHI-TBB packings (10 $\mu\textrm{m}$) and n-hexane was used as a mobile phase with 0.1％ acetic acid and tert-butyl methyl ether. Isocratic elution of ibuprofen at 1.0 $m\ell$/min was performed by changing the mobile phase compositions. The experimental variables affecting the resolution were the compositions of mobile phase and chemical buffer (n-hexane and tert-butyl methyl ether). The resolution between the enantiomers were correlated into the several types of empirical equations including linear form, and their agreements between experimental data and calculated values were examined by the regression coefficient.