Thermal and Structural Study on Liquid-Crystalline Phase Transition in Hexakis(4-(4'-alkyloxy)biphenoxy)cyclotriphosphazene
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- 作者：Keiichi Moriya ; Hiroshi Mizusaki ; Masahiro Kato ; Toshiya Suzuki ; Shinichi Yano ; Meisetsu Kajiwara ; and Kohji Tashiro
- 刊名：Chemistry of Materials
- 出版年：1997
- 出版时间：January 1997
- 年：1997
- 卷：9
- 期：1
- 页码：255 - 263
- 全文大小：311K
- 年卷期：v.9,no.1(January 1997)
- ISSN：1520-5002
文摘
A series ofhexakis(4-(4'-alkyloxy)biphenoxy)cyclotriphosphazene[PN(OC6H4C6H4OC)nH2n+1)2]3(HACP, n = 6-12) compounds was synthesized from sodiumsalts of 4-alkyloxy-4'-hydroxybiphenyl and hexachlorocyclotriphosphazene. The phasetransition and mesogenicityof these substances were studied by FT-IR, X-ray diffraction, and DSCmeasurements andpolarizing microscope observations. In the crystalline-to-smecticC phase transition of HACPwith n = 8, the infrared bands of P=N and P-O-(C)stretching vibrations were found toshift to the lower frequency, indicating the weakening of thecyclotriphosphazene ring inthe liquid-crystalline phase. The X-ray analyzed interlayerspacing 36 Å is smaller thanthe value expected for the fully extended molecular model, indicatingthat the tilt angle ofthe molecules is about 35
from the normal to the layer plane.For HACP with n = 6,monotropic nematic and smectic C phases were found to appear only inthe cooling process.Enantiotropic N and Sc phases were found for the n =7 member. For the HACP with then = 8-12, only an enantiotropic Sc phase was detected.In the series of HACP, thetemperature range of the mesomorphic phase increased with an increasein n. The odd-even effect was not clear, originating from the peculiar shape of thehexakis(4-(4'-alkyloxy)biphenoxy)cyclotriphosphazene with three side chains pointing threeupward and threedownward in both sides of the cyclotriphosphazene ring.
from the normal to the layer plane.For HACP with n = 6,monotropic nematic and smectic C phases were found to appear only inthe cooling process.Enantiotropic N and Sc phases were found for the n =7 member. For the HACP with then = 8-12, only an enantiotropic Sc phase was detected.In the series of HACP, thetemperature range of the mesomorphic phase increased with an increasein n. The odd-even effect was not clear, originating from the peculiar shape of thehexakis(4-(4'-alkyloxy)biphenoxy)cyclotriphosphazene with three side chains pointing threeupward and threedownward in both sides of the cyclotriphosphazene ring.