| Summary: | 碩士 === 國立高雄師範大學 === 化學系 === 94 === Our research results indicate that the compound, benzyl 4-(4’-octoxy biphenyl-4- carbonyloxy)benzoate, which have synthesized by Gray and coworkers in1989 do have mesogenic properties(7). It exhibits the SmA and SmC phases(24).
In order to study the relationship between the molecular structure and the liquid crystal phase behavior, two series of new liquid crystal compounds with cycloalkyl terminal groups were synthesized and their liquid crystal properties studied. The series 1 contains cyclohexyl -methanol as a terminal group while cyclopentylmethanol is used as a terminal group for the series 2.
The results indicate that all the compounds of series 1,except compound 21 are enantiotropic liquid crystals. The compound 21 doesn’t possess any liquid crystal phase. The liquid crystal phase sequence observed of compounds 22~30 depends on the length of alkoxy terminal group. The compounds 22 and 23 have the phase sequence C-SmX-SmA-N-I. While the phase sequence of the compounds 24 and 25 is C-SmX-SmA-I, that of the compounds 26~30 is C-SmX-SmC-SmA-I. A similar situation is observed in series 2. The compound 31 is not a liquid crystal. But all the others compounds 32~40 are enantiotropic liquid crystals. The compounds 32~35 exhibit the liquid crystal phase sequence C-SmA-N-I. Instead of N phase a SmC phase is formed, accompanied with other smectic phases, in all the compounds 36~40.
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