Unsymmetrical alkoxy-substituted triphenylenes: the dependence of mesomorphism on molecular shape
作者:
S. J. CROSS,
J. W. GOODBY,
A. W. HALL,
M. HIRD,
S. M. KELLY,
K. J. TOYNE,
C. WU,
期刊:
Liquid Crystals
(Taylor Available online 1998)
卷期:
Volume 25,
issue 1
页码: 1-11
ISSN:0267-8292
年代: 1998
DOI:10.1080/026782998206443
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
Several series of unsymmetrical hexa-alkoxytriphenylenes have been prepared. For almost every series a maximum in the Colh-I clearing point is found for the most symmetrical triphenylene, i.e. when all six alkoxy chains are of equal length. A similar trend is found for the melting points (Tm), although the effect is not so pronounced. A minimum length is required for formation of a columnar mesophase (Col hd). After this critical value has been reached for short alkoxy chains, much lower Colh-I temperatures are then observed for longer chains. Ordered hexagonal columnar phases required for efficient photoluminescence and electroluminescence have been found for several asymmetrical homologues with comparable TCol-I to those observed for the symmetrical homologues, but also with lower Tm. This may facilitate the preparation of mixtures of triphenylenes with the desired ordered hexagonal columnar phases with a TCol-I and a Tm below room temperature.
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