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Review
. 2009 Nov 20;10(10):4559-4574.
doi: 10.3390/ijms10104559.

Application of Δ- and λ-isomerism of octahedral metal complexes for inducing chiral nematic phases

Hisako Sato  1   2 , Akihiko Yamagishi  3
Affiliations
Review

Application of Δ- and λ-isomerism of octahedral metal complexes for inducing chiral nematic phases

Hisako Sato et al. Int J Mol Sci. .

Abstract

The Delta- and Lambda-isomerism of octahedral metal complexes is employed as a source of chirality for inducing chiral nematic phases. By applying a wide range of chiral metal complexes as a dopant, it has been found that tris(beta-diketonato)metal(III) complexes exhibit an extremely high value of helical twisting power. The mechanism of induction of the chiral nematic phase is postulated on the basis of a surface chirality model. The strategy for designing an efficient dopant is described, together with the results using a number of examples of Co(III), Cr(III) and Ru(III) complexes with C(2) symmetry. The development of photo-responsive dopants to achieve the photo-induced structural change of liquid crystal by use of photo-isomerization of chiral metal complexes is also described.

Keywords: chiral; dopant; metal complex; nematic; twisting power; vibrational circular dichroism.

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Figures

Figure 1.
Figure 1.
The energy-minimized structure of [Δ-[Al(acac)2(L-2) + 2MBBA], showing the mutually left-handed orientation of two MBBA molecules. This figure is a modified version of the one from reference [24].
Figure 2.
Figure 2.
CD spectra of enantiomers in methanol (left) [Ru(acac)2LperC6] (right) [Ru(acac)2Lpara].
Figure 3.
Figure 3.
ICD spectra for EBBA doped Δ- and Λ-enantiomers. (left) [Ru(acac)2LperC12] (right) Λ-[Ru(acac)2Lpara].
Scheme 1.
Scheme 1.
Structure of the Complexes (Illustrated for the Δ-Enantiomers) (modified from reference [24]).
Scheme 2.
Scheme 2.
Structures of the Complexes Studied (Illustrated for the Λ-Enantiomers). This figure is modified one from reference [27].
Scheme 3.
Scheme 3.
Structure of ΔΔ-[Cr(acac)2(taet)Cr(acac)2]. Modified from reference [26].
Scheme 5.
Scheme 5.
Orientation control of liquid crystals under illumination. This is modified one from reference [26].
Scheme 6.
Scheme 6.
Isomerization of photoresponsive chiral Ru(III) complex, [Ru(acac)2(Lazo)per], where acac and cis/trans photoisomerization in methanol by illuminating UV or visible light. Modified from reference [30].
Scheme 7.
Scheme 7.
Δ-[M(acac)2(Lazo)para] (trans form) modified from reference [28].
Scheme 8.
Scheme 8.
Photoresponsive behavior of [Ru(acac)2(Lazo)para].
Scheme 9.
Scheme 9.
Structures of Λ-[Cr(acac)2(2C12)] (acac = acetylacetonate; 2C12 = 4,4’-didodecyloxyated dibenzoylmethanate).
Scheme 10.
Scheme 10.
Real time monitoring of helical pitch modulation by means of vibrational circular dichroism (VCD) spectroscopy. Modified from reference [26].
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References

    1. Kitzerow H-S, Bahr C. Chirality in Liquid Crystals. Springer-Verlag; New York, NY, USA: 2001.
    1. Solladie G, Zimmermann RG. Liquid crystals: A tool for studies on chirality. Angew. Chem. Int. Ed. 1984;23:348–362.
    1. Goodby JW. Chirality in liquid crystals. J. Mater. Chem. 1991;1:307–318.
    1. Lee S-E, Raynes EP. Transmission and amplification of information and properties in nanostructured liquid crystals. Angew. Chem. Int. Ed. 2008;47:2754–2787. - PubMed
    1. Ernst K-H. Amplification of chirality in two-dimensional molecular lattices. Curr. Opin. Colloid Interface Sci. 2008;13:54–59.

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