Photoresponsive chiral dopant nematic liquid crystal Photoresponsive chiral dopant cholesteric +

Example of molecular devices by photoswitching Introduction Example of molecular devices by photoswitching Photoswitching of the reflection color Light-driven molecular machines UV Vis. UV Vis. Y. Li, A. Urban, Q. Li, J. Am. Chem. Soc. 2012, 134, 9573. R. Thomas, Y. Yoshida, T. Akasaka, N. Tamaoki, Chem. Eur. J., 2012, 18, 12337.

Control of helical sense and strength by binaphthyl Introduction Control of helical sense and strength by binaphthyl Proni, G.;Spada, G. P.; Lustenberger, P.; Welti, R.; Diederich, F. J. Org. Chem.2000, 65, 5522−5527.

Conformation of binaphthyl derivatives Introduction Conformation of binaphthyl derivatives

Purpose Change and control of twisting direction, degree of dihedral angle in the binaphthyl ring by photoswitching Molecular design

Change of absorption and CD spectra Result-Photocromism Change of absorption and CD spectra (R)-D1 in n-heptane Substraction of the CD spectra Absorption and CD spectra changes were observed.

Host LCs and Standard LC Left-handed screw sense Experiment Host LCs and Standard LC Host LCs Standard LC (COC) Left-handed screw sense The chiral nematic LC induced by adding (R)-1 –(R)-5 and (S)-1 as a chiral dopnat to PCH or 5CB showed a finger-printed texture in the polarized optical microscope.

Reversible photswitching of helical inversion(1) Result- helical inversion Reversible photswitching of helical inversion(1) Reversible photoswitching of helical inversion was observed along with the photoisomerization →Dihedral angle of binaphthyl rings are controlled

Reversible photswitching of helical inversion(2) Result- helical inversion Reversible photswitching of helical inversion(2) Helical inversion was obsreved only in the (R)-D1.

Helical Twisting Power of D1-D5 and the reversibility Result- HTP and reversibility Helical Twisting Power of D1-D5 and the reversibility (Positive and negative signs represent a right-handed and a left-handed screw sense) Change of Helical Twisting Power was observed along with photoisomerization. →Strength of chiral nematic LC was controlled

Conclusion Conclusion ・The photoresponsive chiral diarylethene derivatives were synthesized and used as chiral dopants to induce th chiral nematic LCs. ・The chiral nematic LCs that included (R)-D1 and (S)-D1 showed a reversible helical inversion in the screw sense. ・ (R)-D1 and (S)-D1 are the first chiral dopnats to induce a helical inversion in a chiral nemtaic LC via the photoisomerization between open and closed forms of the diarylethene moiety.