α, ω-２置換オリゴチオフェンの液晶性に及ぼす置換基の効果 Effect of Substituents on Thermal Behaviors of Oligothiophenes

無置換オリゴチオフェンは6量体以上でないと液晶性を示さず、相転移温度も高い。しかし、α位やω位に適当な官能基を導入すると、チオフェン3量体から液晶性を示すことが報告されている。本研究では、種々な官能基を有するα,ω-２置換チオフェン4量体を合成し、それらの相転移挙動について調べた。置換基と液晶性との相関関係について詳細に検討した。

Disubstituted quaterthiophenes with a variety of function groups such as nitro, phenyl, aldehyde, ester and amide were synthesized. Thermal behaviors of the quaterthiophenes were studied. The dipole moments of each compound were estimated from MOPAC calculations. All the compounds which exhibit liquid crystalline behavior had values of dipole moment in range of 0.11 to 4.9 debye. These results suggest that the value of molecular dipole moment plays an important role in liquid crystallinity.