Photomodulation of a chiral nematic liquid crystal by the use of a photoresponsive ruthenium(III) complex

Tadashi Mitsuoka, Hisako Sato, Jun Yoshida, Akihiko Yamasishi, Yasuaki Einaga

Research output: Contribution to journalArticle

32 Citations (Scopus)

Abstract

We have attempted to control the helical pitch of a chiral nematic liquid crystal by the use of a photoresponsive chiral metal complex. For this purpose, a novel Ru(III) complex [Ru(acac)2(L)] was synthesized, where acac and L denote acetylacetonato and 1,3-bis-{4-[6-(4-phenylazo-phenoxy)-hexyloxy]- phenyl}-propane-1,3 -dionato, respectively. The complex underwent cis-trans photoisomerization in methanol when under UV (λmax = 360 nm) or visible (λmax = 450 nm) light illumination, respectively. When the complex was doped into a room-temperature nematic liquid crystal (ZLI-1132), it induced a chiral nematic phase. Under illumination with UV or visible light, the helical pitch of the chiral nematic phase could be changed reversibly by up to 50%. Corresponding to this change, the helical twisting power (HTP) of the complex varied between 34.0 and 22.0 μm-1, or between -43.9 and -26.6 μm-1 at 35.0 °C, where the positive and negative signs corresponded to the A- and Δ-enantiomers, respectively. This has been the first attempt at combining the ΔΛ chirality of an octahedral metal complex with the cis-trans isomerization of an azobenzene group in the development of a photoresponsive dopant.

Original languageEnglish
Pages (from-to)3442-3447
Number of pages6
JournalChemistry of Materials
Volume18
Issue number15
DOIs
Publication statusPublished - 2006 Jul 25

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Ruthenium
Nematic liquid crystals
Coordination Complexes
Metal complexes
Lighting
Photoisomerization
Propane
Azobenzene
Enantiomers
Chirality
Isomerization
Methanol
Doping (additives)
Temperature
azobenzene

ASJC Scopus subject areas

  • Materials Chemistry
  • Materials Science(all)

Cite this

Photomodulation of a chiral nematic liquid crystal by the use of a photoresponsive ruthenium(III) complex. / Mitsuoka, Tadashi; Sato, Hisako; Yoshida, Jun; Yamasishi, Akihiko; Einaga, Yasuaki.

In: Chemistry of Materials, Vol. 18, No. 15, 25.07.2006, p. 3442-3447.

Research output: Contribution to journalArticle

Mitsuoka, Tadashi ; Sato, Hisako ; Yoshida, Jun ; Yamasishi, Akihiko ; Einaga, Yasuaki. / Photomodulation of a chiral nematic liquid crystal by the use of a photoresponsive ruthenium(III) complex. In: Chemistry of Materials. 2006 ; Vol. 18, No. 15. pp. 3442-3447.
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