Beilstein J. Org. Chem.2012,8, 155–163, doi:10.3762/bjoc.8.16
) was investigated by integrating measurements of helicaltwistingpower with a conformational analysis by DFT calculations and with the prediction of their twisting ability by the surface-chirality method. The two quasi-enantiomeric derivatives induce oppositely handed cholesteric phases when
introduced as dopants in nematic solvents. We evaluated the role of the different conformations of the chiral hydroxyalkyl side chains in determining the helicaltwistingpower: They were found to affect the strength of the chirality transfer, although the handedness of the induced cholesteric phase is
essentially determined by the axial chirality (helicity) of the core of the perylenequinones.
Keywords: chirality; conformational analysis; DFT calculations; helicaltwistingpower; nematic liquid crystals; Introduction
The phenomenon of chiral induction in nematic mesophases has been known for a long time
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Graphical Abstract
Figure 1:
Chemical structure of the helical perylenequinones under investigation: Cercosporin (1) and phleich...
Beilstein J. Org. Chem.2009,5, No. 50, doi:10.3762/bjoc.5.50
relationship between molecular structure, intermolecular interactions, and mesoscale organization. It is known that axially chiral or helical-shaped molecules with reduced conformational disorder are good candidates for high helicaltwistingpower derivatives. In particular, biaryl derivatives are known to be
, allows us to extend our knowledge of the molecular origin of the chirality amplification in liquid crystals and to confirm the simple relationship “molecular P-helicity” → “cholesteric P-handedness” for helical-shaped helicene-like derivatives.
Keywords: chirality; cholesteric; helicaltwistingpower
propensity of a dopant to induce a helical organization in the LC matrix is then quantified by its helicaltwistingpower (HTP), which is defined as [2][3]:
where p is the helical pitch of the cholesteric phase and c and r are the concentration (molar fraction) and the enantiomeric excess of the dopant
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Graphical Abstract
Figure 1:
Schematic structure of a right-handed chiral nematic (cholesteric) phase. Black arrows represent th...