Twelve triphenylene discogens with unsaturated periphery (abbreviated as C18H6(OC5H11)6−x (OR) x (x = 1, 2, 3), R = -C3H6CH == CH2 (a), -C3H6C C ≡CH (b), -C2H4OCH== CH2 (c)) were synthesized and characterized. The thermotropic liquid crystal properties were studied by using polarized optical microscopy, differential scanning calorimetry and X-ray diffractometry. The results showed that all triphenylenes exhibited hexagonal columnar mesophase. The thermotropic studies showed that series a (alkene periphery) exhibited higher clearing points than the corresponding series b (alkyne periphery), while series c (vinyloxy periphery) exhibited highest clearing points and widest mesophase temperature ranges. We also found that the symmetric discogens sym-C18H6(OC5H11)3(OR)3 displayed higher melting points and clearing points than the asymmetric ones asym-C18H6(OC5H11)3(OR)3.
具有不饱和外围的十二个苯并
菲二元(缩写为
C18H6(OC5H11)6−x (OR) x (x = 1, 2, 3),R = -C3H6CH ==
CH2 (a),-C3H6C C ≡CH (b),合成并表征了-C2H4OCH== (c))。利用偏光显微镜、差示扫描量热法和X射线衍射法研究了热致液晶特性。结果表明,所有苯并
菲均呈现六方柱状中间相。热致研究表明,a系列(烯烃外围)比相应的b系列(炔外围)表现出更高的清亮点,而c系列(
乙烯基氧基外围)表现出最高的清亮点和最宽的中间相温度范围。我们还发现对称的disogens sym- (OC5H11)3(OR)3 比不对称的disogens asym- (OC5H11)3(OR)3 显示出更高的熔点和澄清点。