Metal containing liquid crystals

Finally, there are groups of liquid crystals where, at the current time, force fields are not particularly useful. These include most metal-containing liquid crystals. Some attempts have been made to generalise traditional force fields to allow them to cover more of the periodic table [40, 43]. However, many of these attempts are simple extensions of the force fields used for simple organic systems, and do not attempt to take into account the additional strong polarisation effects that occur in many metal-containing liquid crystals, and which strongly influence both molecular structure and intermolecular interactions. 

Metal-containing liquid crystals opened the way to new geometries and new topologies, in comparison with wholly organic materials, and allowed further investigation of the relationship between structure and mesomorphic properties. Mononuclear (Ni, Cu, Rh, Pd, Pt, V, Ag, Au, Zn, rare earths) and dinuclear (Rh, Mo, Ru, Ni, Cu and Pd) coordination complexes containing liquid crystals were prepared and studied during the last decade [5]. 

One of the earlier contributions to the revival of metal-containing liquid crystal systems was the synthesis of the ort, ti-metallated palladium complexes of mesogenic azobenzenes 91, 92 by Ghedini and co-workers, which represented the first systematic attempt to coordinate metals to known liquid-crystal systems. 

It is now certain that metal carboxylates were the first metal-containing liquid crystals, and were first reported in 1855 with Heinz s work on magnesium tetradecanoate [4]. Then, many other mesomorphic metal carboxylates, with the general formula M(02C—C H2 +i) , were prepared [150]. They showed thermotropic lamellar and columnar mesophases, but also, when dissolved in water or alkanes, lyotropic mesophases. 

Giroud-Godquin, A.-M. Metal-Containing Liquid Crystals. In Handbook of Liquid Crystals Demus, D. Goodby, J. Gray, G. W. Spiess, H.-W. Vill, V. Eds. Wiley-VCH Weinheim, 1998 Chapter XIV, pp 901-932. 

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