Ferroelectric Liquid Crystals Induced by Atropisomeric Biphenyl Dopants: Dependence of the Polarization Power on the Nature of the Symmetry-Breaking Groups
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- 作者：Despina Vizitiu ; Carmen Lazar ; Joshua P. Radke ; C. Scott Hartley ; Matthew A. Glaser ; and Robert P. Lemieux
- 刊名：Chemistry of Materials
- 出版年：2001
- 出版时间：May 2001
- 年：2001
- 卷：13
- 期：5
- 页码：1692 - 1699
- 全文大小：193K
- 年卷期：v.13,no.5(May 2001)
- ISSN：1520-5002
文摘
Four new chiral dopants containing an atropisomeric biphenyl core derived from 4,4'-dihydroxy-2,2',6,6'-tetramethylbiphenyl with different symmetry-breaking groups at the 3,3'-positions (X = F, Cl, Br, and Me) were synthesized in optically active form. These dopantswere used to induce ferroelectric SmC* liquid crystal phases in four SmC hosts with differentcore structures. Polarization powers 
delta.gif" BORDER=0 >p were measured as a function of the SmC host andcompared to delta.gif" BORDER=0 >p values previously obtained for an analogous atropisomeric dopant with X =NO2. Theoretical conformational analyses for rotation of the atropisomeric cores about theC-O bonds of the ester groups linking the core to the side chains were performed at theB3LYP/6-31G(d) level and used in calculating Boltzmann-weighed statistical averagetransverse dipole moments <
> for the core-diester units. The <> values were used tonormalize delta.gif" BORDER=0 >p to study the influence of the symmetry-breaking groups X on the polar orderingof the dopants. Variations in delta.gif" BORDER=0 >p(norm) are rationalized by considering models describing eitherachiral or chiral distortions of the zigzag binding site model of the SmC host. Results showthat the symmetry-breaking groups X exert a unique influence on polar ordering of thedopants in the phenylpyrimidine host PhP1 that is consistent with a model in which chiralitytransfer via core-core interactions between dopant and host molecules causes a chiraldistortion of the zigzag binding site.
delta.gif" BORDER=0 >p were measured as a function of the SmC host andcompared to delta.gif" BORDER=0 >p values previously obtained for an analogous atropisomeric dopant with X =NO2. Theoretical conformational analyses for rotation of the atropisomeric cores about theC-O bonds of the ester groups linking the core to the side chains were performed at theB3LYP/6-31G(d) level and used in calculating Boltzmann-weighed statistical averagetransverse dipole moments <> for the core-diester units. The <> values were used tonormalize delta.gif" BORDER=0 >p to study the influence of the symmetry-breaking groups X on the polar orderingof the dopants. Variations in delta.gif" BORDER=0 >p(norm) are rationalized by considering models describing eitherachiral or chiral distortions of the zigzag binding site model of the SmC host. Results showthat the symmetry-breaking groups X exert a unique influence on polar ordering of thedopants in the phenylpyrimidine host PhP1 that is consistent with a model in which chiralitytransfer via core-core interactions between dopant and host molecules causes a chiraldistortion of the zigzag binding site.