Disco tic

K., Chanzy, H.D., Sirringhaus, H. and Friend, R.H., Meso-epitaxial solution-growth of self-organizing disco tic liquid-crystalline semiconductors, Adv. Mater, 15, 495 99, 2003. 

H., Pakula, T. and Mullen, K., A zone-casting technique for device fabrication of field-effect transistors based on disco tic hexa-peri-hexabenzocoronene, Adv. Mater, 17, 684-689, 2005. 

Grigoriadis, C., Haase, N., Butt, H.J., MtUlen, K., Floudas, G., 2010. Negative thermal expansion in disco tic liquid crystals of nanographenes. Adv. Mater. 22,1403-1406. 

The metal atoms can be bond by coordination bonds, either in a slat-like fashion or, more rarely, by c-bonds [284]. Irrespective of the nature of the bonds the compounds may be called metallomesogens [274]. Depending on the geometry of the molecules, metallomesogens can be calamitic or disco-tic. Rod-like mercury containing compounds were prepared by Vorlander s group [5, 285]. 

Most of the discotic compounds consist of a central core to which are attached 3-12 substituents, which may contain ring systems and/or flexible chains. The most simple central core is the benzene ring, which was used for the synthesis of the first disco-tic compounds [7]. 

In discotic systems, the roles of ATu and K22 are reversed, because in such phases the bend deformations require the lowest energy [181]. Measurements of splay and bend constants in a homologuous series of discotic n-hexa(alkanoylox)truxenes [76] revealed that K22 is always smaller than A, . The splay/bend ratio approached unity at the high temperature transition to the columnar phase. Qualitatively different results have been obtained, however, by Raghunathan et al. [75], who found K22>Kn in a disco-tic nematic phase enclosed between two columnar phases. The authors interpreted this unexpected result as being a consequence of short-range columnar order. 

In his treatment of the general problem of the stability of iow-dimensional systems, Landau also considered the case of a three-dimensional body in which the density is a periodic function of two dimensions only. In the light of his analysis, he concluded Thus, such a structure could in theory exist, but it is not known whether they do in fact exist in Nature [20]. The structure envisaged by Landau is, of course, an accurate description of the columnar phase of disco-tic molecules that was proposed originally [1], i.e., liquid-like columns forming a two-dimensional lattice. 

One-dimensionality of charge and exciton transport is a unique feature of HATn disco-tic liquid crystals. The exciton transfer anisotropy is > 10" [40]. Given the large bandwidth along the columns, it is difficult to envisage an intercolumnar transfer unless the... 

Ohta, K. Discotic Liquid Crystals of Transition Metal Complexes. 4 1 Novel Disco tic Liquid Crystals Obtained from Substituted Bis(dithiolene)nickel Complexes by a New Method. Mol. Cryst. Liq. Cryst.,1987 Gordon and Breach Science Publishers S.A., Vol 147, pp 15-24. 

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