2. How is helical inversion?
introduction
How is helical inversion?
H.Hayasaka, et al. J. Am. Chem. Soc. 2012, 134, 3758−3765

3. Structures which induce helical inversion
introduction
Structures which induce helical inversion
Type1:Intrinsic chirality
Type2:dinamic conformation change
R. Elelkema, et al. J. Am. Chem. Soc. 2006, 128,
H.Hayasaka, et al. J. Am. Chem. Soc. 2012, 134, 3758−3765

4. purpose
Design strategy based on the chiral conflict and equilibrium shifting between multiple chiral moieties in a singl molecule and control helical inversion
Molecular design

5. Absorbance and CD spectra of (S,R,S)-1a
Result - photoisomerzaion
Absorbance and CD spectra of (S,R,S)-1a
10μm in hexane
Absorption and CD spectra changes were observed.

6. Measurement of cholesteric liquid crystal handedness
Result – helical inversion
Measurement of cholesteric liquid crystal handedness
Reversible photoswitching of helical inversion was observed along with the photoisomerization

7. Helical inversion and measurement of HTP
Result – HTP
Helical inversion and measurement of HTP
(Positive and negative signs represent a right-handed and a left-handed screw sense)

8. Mechanism of helical inversion
Discussion
Mechanism of helical inversion

9. Conclusions Conclusion
・ A series of azoarene compounds containing axially chiral moieties with different chiral
configureation was synthesized.
・ The chiral confict and equilibrium shifting between opposite chiral configuration in these
compounds was used to promote the handedness inversion.
・ Handedness was found in different LC hosts and the HTPs for both stated were moderate to
high.