Disc-Like Mesogens: A Classification

Abstract

Five mesomorphic phases are described in several disc-like liquid-crystals. They are hexaalkanoyloxy benzenes, triphenylenes or truxenes, hexa-alkoxy triphenylenes, hexa-benzoates of triphenylene. Several of these compounds exhibit a complex polymorphism. Informations on the structures of these phases have been obtained by means of X-Ray diffraction; except a ND namatic phase all the others one are columnar phases. At the same time a systematic study has been performed by the well known method of isomorphy. All these results allow us to propose a general classification of these phases.

Isocyano-Triphenylene Complexes of Gold, Copper, Silver, and Platinum. Coordination Features and Mesomorphic Behavior

“…The change and the redistribution of the electron density across the aromatic skeleton in these systems, and the consequent change of molecular interactions, modifies markedly the range of existence of the mesophases. 28,35,36 An interesting variation of these two kinds of triphenylene systems is to connect the metal fragment to the triphenylene core using a short conjugated linker. The isocyanide group is an efficient linker, and we are reporting here the synthesis of the previously unreported 1-isocyano-2,3,6,7,10,11-hexadodecyloxytriphenylene (CN-TriPh) ligand and its stable isocyanide-triphenylene metal complexes with gold(I), copper(I), silver(I) and platinum(II), and verify how the supramolecular structure and the properties of the original organic system change.…”

Optical Compensation Film for FPD Produced by Liquid Crystalline Monomer

“…Discotic Liquid Crystalline Compound [4] Discotic liquid crystal compound shows the normal crystalline phase, the columnar phase, the discotic nematic (N D ) phase and the isotropic phase (Fig. 5) [5]. Luckhurst et al have suggested the appearance of a wide, nematic phase, the same as that the calamitic liquid crystal that occurs as a result of calculation of the relationship between the phase structure and the transition point, assuming the discotic liquid crystal is a smooth and rigid plane table using Gay-Berne potential [6].Most of the discotic liquid crystal compounds, however, preferentially show the columnar phase, and few of them form the N D phase (Fig.…”

Measurements of the ratio of the Frank constants for splay and bend in nematics of disc-like molecules

“…These materials show a normal sequence in the occurrence of different mesophases. When cooling the isotropic liquid of these triphenylene derivatives, nematic, columnar and crystalline phases are obtained (see figure 1), in contrast to the alkanoyloxytruxenes which exhibit an inverted nematic phase, viz, a nematic phase at a lower temperature than a columnar phase [3,4]. In order to investigate whether the results found for the inverted nematic phase, exhibited by the truxene derivatives, are characteristic for the behaviour of nematics consisting of discoid molecules we have studied the normal nematic phase exhibited by these triphenylene derivatives.…”

“…The phase difference (AO) between these two light waves after passing through a sample with thickness d is given by (see e.g. [6]) AO = 2ird(ne n0)11, (3) where A is the wavelength of the polarized light. The ordinary refractive index is not dependent on rotation of n in the xz plane, whereas the extraordinary refractive index depends on the rotation of n as given by no = n1; ; = n11n_LI(r4cos2 0 + ni sin' 0)1/2, (4) where n, and no are the refractive indices perpendicular and parallel to the director, respectively, and 0 is the angle between the director and the direction of the magnetic field.…”