Mesophases calamitic

Note 5 If the mesogenic side-groups are rod-like (calamitic) in nature, the resulting polymer may, depending upon its detailed structure, exhibit any of the common types of calamitic mesophases nematic, chiral nematic or smectic. Side-on fixed SGPLC, however, are predominantly nematic or chiral nematic in character. Similarly, disc-shaped side-groups tend to promote discotic nematic or columnar mesophases while amphiphilic side-chains tend to promote amphiphilic or lyotropic mesophases. 

Figure 7.2 Schematic representation of N, SmA and SmC calamitic mesophases with the corresponding director vector n.

Bernardinelli, G, Biinzli, J.C.G., Deschenaux, R., and Guillon, D. (1998) Bent tridentate receptors in calamitic mesophases with predetermined photophysical properties new luminescent lanthanide-containing materials. Journal of the American Chemical Society, 120, 12274. 

Liquid-crystalline phases are characterized to some degree by the shape of the molecules and by their packing arrangements and ordering in the mesomorphic state. Typically, molecules can have cither disc- or rod-like shapes and can form discotic or calamitic mesophases, respectively. Ferrocene liquid crystal systems that have so far been synthesized tend to have molecular structures that are lath- or rod-like in shape, and consequently the phases observed are calamitic. However, this does not preclude the possibility that a polysubstituted ferrocene could be prepared where the molecular shape is disc-like, thereby holding out the prospect of possibly producing discotic/columnar phases. 

Calamitic mesophases were the first liquid crystals to be found more than 100 years ago. In 1888, the botanist... 

Discotic liquid crystals arise from disc-shaped molecules as nematic or cholesteric mesophases. Their structural characteristics are similar to that of their respective calamitic mesophases, that is, the normals... 

The structural features of the inherent structures yielded important information on the interplay between the orientational and translational order in the calamitic mesophases [144]. It follows from Fig. 22b that quenching results in enhanced orientational order for inherent structures than the corresponding pre-quenched configurations. We now examine how the inherent structures evolve as revealed by the pair distribution functions that were obtained by averaging over the quenched configurations. An analysis through the parallel radial distribution function g (V ), which depends only on rj, the pair separation r, parallel to the director n, reveals a remarkable feature as illustrated in Fig. 26a. The onset of growth of the orientational order in the vicinity of the I-N transition induces a... 

Due to the disc-like geometry of the porphyrin macrocycle, discotic mesophases have generally been the most common for porphyrin liquid-crystalline materials. The first porphyrin liquid crystals featuring rod-like calamitic mesophases were described by Bruce and coworkers using substituted 5,15-di(phenyl) zinc porphyrin complexes as the basic molecular building block.The first materials... 

In the following sections some of the more common liquid crystal textures utilized in the classification of thermotropic calamitic mesophases are described. It should be noted that similar examinations of defects are used to classify discotic, polymeric, and lyotropic phases. 

Calamitic mesophase - a mesophase formed by molecules or macromolecules with rod or lath-like molecular structures. 

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