Spontaneous chirality induction and enantiomer separation in liquid crystals composed of achiral rod-shaped 4-arylbenzoate esters.
The discovery of spontaneously induced chirality and enantiomeric separation in liquid crystal and soft crystal systems composed of achiral rod-shaped 4-arylbenzoate esters is described. Negligibly small circular dichroism (CD) signals are produced in the smectic A (SmA) phases of these substances, and the signals were found to increase with increasing smectic order. Since the advent of chirality occurs in freely suspended films, it is not a consequence of surface effects. Both positive and negative CD signals are observed with equal probability at different positions in these films. Vibrational CD spectroscopy and theoretical calculations are used to analyze the conformational changes that are associated with the induced chirality of the rod-shaped molecules. The results show that the phenomenon is caused by the twisting of biphenyl bond associated with the ester moiety in 4-arylbenzoate esters.
Jeong
Hyeon Su
HS
Department of Chemical and Biomolecular Engineering (BK-21), Korea Advanced Institute of Science and Technology, 373-1 Guseong-dong, Yuseong-gu, Daejeon 305-701, Korea.
Tanaka
Shingo
S
Yoon
Dong Ki
DK
Choi
Suk-Won
SW
Kim
Yun Ho
YH
Kawauchi
Susumu
S
Araoka
Fumito
F
Takezoe
Hideo
H
Jung
Hee-Tae
HT