• Bulletin of the Korean Chemical Society
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• 제4권4호
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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.

• 한국인쇄학회지
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• 제16권2호
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• pp.37-44
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• 1998

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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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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• 제30권7호
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• pp.1634-1636
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• 2009

• Bulletin of the Korean Chemical Society
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• 제27권9호
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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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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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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.

• 공업화학
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• 제30권2호
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• pp.247-253
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• 2019

본 연구에서는 분자 내 하나의 페닐고리의 4-, 3,5-, 또는 3,4,5- 위치에 아조-메소젠기가 각각 결합된 화합물들을 합성하고 이들의 액정성 및 광화학성에 대하여 조사하였다. Azo1과 Azo2 계열의 화합물은 각각 선형과 평면형의 구조이며, Azo3 계열의 화합물은 비교적 부피가 큰 구조를 하고 있는 것으로 조사되었다. 화합물 BA-Azo2와 BA-Azo3는 액정성을 나타내지 않았고, BE-Azo1와 BE-Azo2는 단방성 액정성을, 나머지 화합물들은 양방성 액정성을 나타냈다. 이러한 액정 거동은 분자 내 아조-메소젠기의 존재로부터 부여된 것으로 액정성을 나타내는 대부분의 화합물들은 스멕틱상을 형성하였다. 그리고 모든 RM-AzoX 화합물들은 분자 내 아조기의 존재로 인하여 광 이성질현상을 나타냈으며, 광 이성질화 속도는 RM-Azo3 < RM-Azo1 < RM-Azo2의 순서로 조사되었으며, 이는 아조벤젠기 주위의 입체 장애에 의존하는 것으로 생각된다. 이러한 결과들로부터, 화합물의 액정성과 광화학적 성질들은 분자 내 페닐고리에 결합된 아조-메소젠기의 결합위치나 개수에 기인한다는 것을 알 수 있었다.

• 한국결정성장학회지
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• 제26권6호
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• pp.232-237
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• 2016

약물의 공결정 형성은 결정구조를 디자인하여 물리적인 성질을 제어하는 방법으로 각광받고 있다. 특히, 밀링 결정화법은 약물 공결정의 형성 여부를 판단하기 위한 스크리닝 기법으로 널리 사용되고 있는데, 대부분의 경우에 소량의 액체를 첨가하는 것이 필요하다. 본 연구에서는 액체의 첨가가 없는 밀링법을 가능하게 하기 위해서, ibuprofen/nicotinamide의 공결정화에 온도가 미치는 영향을 살폈다. 액체질소 냉각 온도와 상온에서의 밀링을 비교하였을 때, 액체질소 냉각 상태에서 공결정화가 상대적으로 효과적으로 진행된 것을 XRD, DSC 등의 분석법을 이용하여 확인하였다. 이러한 결과는 원료 물질의 유리전이 온도 이하에서 밀링하였을 때 분자의 운동성이 제한되어, 원료 결정구조의 파쇄와 공결정 유도가 효과적으로 일어나는 것으로 해석할 수 있다. 본 결과가 약물 밀링 공결정화에 응용되기 위해서는 여러 약물 공결정에 대한 추가 연구가 필요하다.

• 한국인쇄학회지
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• 제19권1호
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• pp.1-3
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• 2001

No abstract, See Full-text.

• 대한화학회지
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• 제42권6호
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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.