• Bulletin of the Korean Chemical Society
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• v.4 no.4
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• pp.176-180
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• 1983

A series of new liquid crystalline compounds having two identical mesogenic terminal units, the 4-(p-nitrobenzoyloxy)phenoxy group, attached to both ends of a central polymethylene spacer of various lengths was prepared. The mesomorphic properties of the compounds were investigated by differential scanning calorimetry (DSC) and by polarizing microscopy. Almost all of the compounds formed monotropic nematic mesophases. The trimethylene spacer compound was found to be non-liquid crystalline, while the one with the hexamethylene central spacer was enantiotropic. A thermodynamic analysis was performed for the phase transitions of the compounds and the results are discussed in relation to their liquid crystal properties.

• Journal of the Korean Graphic Arts Communication Society
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• v.16 no.2
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• pp.37-44
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• 1998

• 한국정보디스플레이학회:학술대회논문집
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• 2003.07a
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• pp.604-607
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• 2003

Three ring type LC compounds substituted with isothiocyanato group and fluoro atoms in phenyl ring were synthesized, and blended with KL-series LC mixtures for TV application of TN and IPS-mode. Clearing temperature of new LC mixtures are shown $10{\sim}35{\square}$ higher than commercial mixtures. And response time was also improved $10{\sim}20%$ faster than conventional LC mixtures.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1634-1636
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• 2009

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1364-1370
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• 2006

New liquid-crystalline biphenyl carboxylates with an achiral swallow-tail derived from 1,3-dialkoxy-2-propanol $[(ROCH_2)_2CHOH$] where R is methyl, ethyl, propyl, butyl, $CH_2CF_3$, and $CH_2CF_2CF_3$ were prepared. These achiral liquid crystals having 1,3-dialkoxy-2-propyl moieties exhibit diverse phase sequences [I-SmA-(SmC)-(SmCalt)-Cr] depending on the substituent R group of the swallow-tail. The compounds carrying a fluorinated swallow-tail exhibit antiferroelectric-like smectic C phases, and their temperature ranges are broader than the corresponding non-fluorinated swallow-tailed ones.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.8-9
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• 2009

After reviewing the principle of a new display utilizing bent-core liquid crystals, we summarize the advantages and problems of this display. Then we will introduce our effort to overcome these problems mostly by synthesizing new materials. We obtained a variety of newly synthesized compounds showing the $SmAP_R$ phase. Mixing was effective to decrease and widening the temperature range of the $SmAP_R$ phase.

• Applied Chemistry for Engineering
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• v.30 no.2
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• pp.247-253
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• 2019

In this study, compounds with azo-mesogenic groups at 4-, 3,5-, or 3,4,5-positions of one phenyl ring were synthesized, and their liquid crystallinity and photochemistry were investigated. The compounds in the Azo1 and Azo2 series had linear and planar geometries, respectively, while those in the Azo3 series had relatively bulky structures. Compounds of BA-Azo2 and BA-Azo3 did not show any liquid crystallinity. Compounds of BE-Azo1 and BE-Azo2 exhibited a monotropic liquid crystallinity, while the other compounds showed an enantiotropic liquid crystallinity. The liquid crystalline behavior was imparted by the azo-mesogenic groups, and most of the liquid crystalline compounds formed a smectic phase. All the RM-AzoX compounds exhibited photoisomerism because of the presence of the azo groups in the molecule. The rate of photoisomerization followed the order of RM-Azo3 < RM-Azo1 < RM-Azo2 and was considered to depend on the steric hindrance around the azobenzene groups in the molecule. These results suggest that the liquid crystallinity and photochemical property of the compounds are affected by the position or the number of azo-mesogenic groups phenyl ring of the molecule.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.232-237
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• 2016

Cocrystallization of active pharmaceutical ingredients has been widely recognized as a versatile tool to regulate the physical properties of pharmaceutical compounds through designed crystal structures. Grinding or milling has been especially useful to screen the feasibility of cocrystal formation, and the addition of a small amount of liquid is routinely necessary. In the present study, the effect of temperature was studied for the milling cocrystallization of ibuprofen and nicotinamide to establish a liquid-free method. The milling-induced cocrystallization was more effective with liquid nitrogen cooling than at room temperature, which was confirmed by XRD and DSC analyses. This behavior was attributed to the limited molecular mobility below the glass transition temperatures of the cocrystal components, which made it effective to destruct the crystals of raw materials and consequently form the ibuprofen/nicotinamide cocrystal. Further studies would be necessary to establish the utility of the current conclusion to the field of pharmaceutical crystallization.

• Journal of the Korean Graphic Arts Communication Society
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• v.19 no.1
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• pp.1-3
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• 2001

No abstract, See Full-text.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.679-695
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• 1998

A series of ${\alpha}{\omega}-bis[4-(4'-(S)-(+)-2-methylbutylbiphenyl-4-carboxy)phenoxy]alkanes$, were synthesized, and their thermal and liquid crystalline properties were studied. The chain length of the central polymethylene spacers, x, of the chiral twin compounds was varied from 3 to 12. These compounds were characterized by elemental analysis, IR and NMR spectroscopy, differential thermal analysis (DSC), and crosspolarized microscopy. All compounds were found to be enantiotropic liquid crystalline, and the values of melting $(T_m)$ and isotropization temperature $(T_i)$ as well as ${\delta}H_I$ and ${\delta}S_I$ decreased in a zig-zag fashion, revealing the so called odd-even effect as x increased. Their mesomorphic properties fell into four categories depending upon x; (a) compounds with x=3, 4 and 5 formed only a cholesteric phase on heating, while on cooling they went through two transitions of isotropic (I)-to-cholesteric (Ch) and Ch-to-smectic $A\;(S_A)$ phases before crystallization. (b) compounds with x=6, 8 and 10 exhibited only a cholesteric phase both on heating and on cooling. (c) compounds with x=7 and 9 went through three transitions of crystal $(C)-to-S_A,\;S_A-to-Ch,$ and Ch-to-I phases on heating while on cooling they went through four transitions of I-to-Ch, $Ch-to-S_A,\;S_A-to-Smectic\;C\;(S_C),\;and\;S_c-to-C$ phases in that order, and (d) compounds with x=11 and 12 went reversibly through four transitions of $C-to-S_C,\;S_C-to-S_A,\;S_A-to-Ch,$ and Ch-to-I phases.