含氟链不对称苯并菲盘状液晶的合成及疏氟效应对介晶性的影响

盘状液晶分子中引入氟代烃链并利用疏氟效应（fluorophobic effect）能有效稳定分子的柱状堆积；低对称性的盘状分子有较低的熔点和宽的介晶相温度范围．基于此，本文设计并合成了一系列半氟酯链的不对称苯并菲化合物C18H6（OCnH2n＋1）4（OCH3）（O2CC2H4C6F13）（1），及相对应的不含氟化合物C18H6（OCnH2n＋1）4（OCH3）（O2CC8H17）（2），n=4—8．化合物结构通过核磁和质谱表征．介晶性通过差示扫描量热法和偏光显微镜进行了研究．结果显示：化合物均为柱状互变热致液晶．含氟链化合物1a—1e与相对应的化合物2a-2e比较，有更高的熔点和清亮点．合成的多数化合物为室温液晶．

Synthesis of unsymmetric triphenylene discotic liquid crystals with semi-fluorinated chain and the influence of fluorophobic effect on mesogenic behaviors

The fluorophobic effect of semi-fluorinated chain of discotic molecule efficiently improves the stability of columnar mesophase. Low symmetric discogens exhibit decreased melting points and wide mesophase ranges. A series of triphenylene derivatives 1, C18H6（OCnH2n＋1）4（OMe）（O2CC2H4C6F13）, and their hydrocarbon analogues 2, C18H6（OCnH2n＋1）4（OMe）（O2CC8H17）, n = 4-8, were synthesized for the investigation of the influence of semi-fluorinated peripheral chain and molecular symmetry on mesomorphism. The structures were characterized with ^1H NMR and Mass. The mesomorphism was studied with differential scanning calorimetry （DSC） and polarizing optical microscopy （POM）. The results showed that all triphenylene derivatives exhibited enantiotropic columnar mesophase. The semi-fluorinated triphenylenes 1a-1e displayed higher melting points and more clear points than their hydrocarbon analogies 2a-2e. Most of them were in columnar mesophase at room temperature.