Chirality in Liquid Crystals

If multiple springs are packed together closely, you quickly notice that an overall twist appears to develop. Each spring, when packed next to its neighbor, will be rotated by a small angle as the threads slot into each 

FIGURE 2.9 Cholesterol derivatives were the first liquid crystals investigated. Cholesterol benzoate shown here is a chiral molecule and forms a cholesteric phase. 

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Kitzerow HS, Bahr C (2001) Chirality in liquid crystals. Springer, New York... 

The induction of chirality in liquid crystals (LCs) has a long history [100-104]. The supramolecular induction can be used to assign absolute configurations [105-108], conformations of molecules [109,110] and the interplay between inter- and intra-molecular interactions [111], and models can be developed to justify the sense of the inductions that are observed. Twisting powers of dopants—the twist per mole—can be pushed to extraordinary values [112]. Given the history and vast body of work, we will focus here on the more contemporary aspects of work in this area. 

Kitzerow, H.-G. Twist grain boundary phases. In C. Bahr, H. Kitzerow Eds. Chirality in liquid crystals. New York Springer Vet ag, 297 2000. ... 

Goodby J W 1998 Symmetry and chirality in liquid crystals Handbook of Liquid Crystals Vol 1. Fundamentals ed D Demus, J Goodby, G W Gray, H-W Spiess and V Vill (New York Wiley-VCH)... 

G. P. Crawford, D. Svensek, and S. Zumer, in Chirality in liquid crystals, H. S. Kitzerow and C. Bahr, Edts., Springer-Verlag, New York, (2001). 

H.-S. Kitzerow, C. Bahr (eds.). Chirality in Liquid Crystals (Springer, New York, 2001)... 

R. EeUcema, B.L. Feringa, Amplification of chirality in liquid crystals. Qrg. Biomol. Chem. 4, 3729-3745 (2006)... 

Kitzerow, H. -S. Bahr, C., Eds. Chirality in Liquid Crystals-, Springer-Verlag New York,... 

In recent years chirality in liquid crystals has developed into a very important area of liquid crystal research. Chiral materials are reqtrired for the chiral nematic (N ) phase and the ferroelectric chiral smectic C (S ) phase for a wide variety of applicatiorrs. As... 

Due to the important role of chirality in liquid crystals, a large number and variety of chiral chemical compounds have been developed. This chapter describes the most important molecular fragments and classes of chemical structures (Section 4.2) which provide both chirality and mesogenic properties. The form of chiral phases depends on the principles of the mesophase formation (Section 4.3). Some relations between the molecular chirality and the appearance of mesophase chirality are discussed and chiral dopants are classified (Section 4.4). With respect to the mesophase behavior and to optical and electro-optical applications, it is important to know how the mesogenic chirality can be modified, e.g., chemically by photoisomerization, or by changes of temperature or composition for certain suitable compounds (Section 4.5). Finally, chiral liquid crystals provide not only optical and electro-optical applications but also applications in Chemistry, e.g., as chiral solvents for synthesis, chiral stationary phases in chromatography, or chemical sensors (Section 4.6). 

The chirality in liquid crystal elastomers can be at the origin of additional physical properties such as ferroelectricity, pyroelectricity, circular dichro-ism, and nonlinear optics coupled to the polymer network. Applying external mechanical fields to the elastomers consequently causes electro-... 

Finally, we conclude that with his interest in chirality in liquid crystals for many years now, an interest we have shared, Professor Gerd Heppke has demonstrated his perspicacity and good taste in scientific problems. May you have many more years of happy experiences offered by the ineluctable pleasures of chirality—and the Broken Symmetries of Life—particularly broken time reversal symmetry. 

Chirality in liquid crystals / editors, Heinz-Siegfried Kitzerow, Christian Bahr. p. cm. — (Partially ordered systems)... 

It is indeed a pleasure for me to write the foreword for this volume brought out in honor of Prof. Gerd Heppke to felicitate him on his reaching sixty years of age. It comprises a collection of papers by friends and admirers on the broad theme of chirality in liquid crystals, which is an area of current interest and one in which Prof. Heppke himself has made significant contributions. 

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