Die Polymorphie der kristallin-flüssigen Modifikationen in der homologen Reihe der 4′n-Alkoxy-3′-nitrodiphenyl-4-carbonsäuren¹

Abstract

Some members of the homologous series of the 4'-n-alkoxy-3'-nitrodiphenyl-4-carboxylic acids, which have been already described by GRAY, were prepared. Their polymorphism in the smectic state was investigated. The relations of selective miscibility between the liquid crystalline modifications have been explored by the investigation of binary diagrams of state. By the use of the rule of selective miscibility, we can state: In this homologous series nematic and smectic A-and Cmodifications occur. The two highest members of the series have a new smectic modification marked with the symbol D.In der vorhergehenden Mitteilung 2 wurde die kristallin-flüssige (kr. -

Helical Networks of π‐Conjugated Rods – A Robust Design Concept for Bicontinuous Cubic Liquid Crystalline Phases with Achiral Ia3¯d and Chiral I23 Lattice

“…They can deviate from these values, for example, if the alkyl chain at the apex is especially long (X = OC 10 H 21 ), or as the length and shape of the core is changed, though the fundamental phase sequence remains the same. [117] Depending on the contribution of the substituent to the volume effect and the twist, the lattice parameter can increase, as observed for the BABHs and ANBCs, [101,103,104,107,108] remain almost constant, as reported here for compounds 3/ m X n and 3a/Y, or even decreases with increasing volume of the substituents, as recently reported for benzil-based polycatenars. [154] However, in all cases, the twist angle increases with the apex volume, leading to the sequence Ia3 d (L) -I23-Ia3 d (S) .…”

“…For example, robust bicontinuous cubic phases were even found for polyaromatic rods with only two alkyl chains (Figure 9a, e.g., BABHs [107,108] and the hydrogen-bonded dimers of the ANBCs, see Figure 1c,d). [16,101,103,104] In these cases, alkyl chain intercalation or replacing the alkyl chains by perfluorinated chains [141,142] or by adding bulky silyl groups [74,108] provides the required interfacial curvature for Cub bi phase formation. Permanent molecular chirality can further support the helical twist, leading to a series of chirality frustrated LC phases.…”

“…[11][12][13][14][15][16] Therefore, Cub bi phases are usually not predictable and appear only in narrow temperature ranges for few well designed compounds (Figure 1c-f). The most prominent are rod-like hydrogen bonded dimers of 4′-n-alkoxy-3′-nitrobiphenyl-4-carboxylic acids (ANBCs), [100][101][102][103][104] the dibenzoylydrazines (BABHs) [105][106][107][108][109][110][111] (Figure 1c,d), [16,17,108,110] and tetracatenar molecules, which can have either a symmetric or a nonsymmetric distribution of the alkyl chains (Figure 1e,f). [112][113][114][115][116][117][118][119][120][121][122][123][124] Nevertheless, even these compounds are very sensitive to minor molecular structural variations.…”

Dynamic Mirror‐Symmetry Breaking in Bicontinuous Cubic Phases

“…The structural insight acquired herein promises to end one of the longest persisting mysteries in the liquid crystal field, that started with the discovery of the “smectic-D” phase over half a century ago. [ 31 , 32 ] But the importance of this finding goes far beyond the systems discussed herein and contributes to the general understanding of symmetry breaking in soft condensed matter.…”

Elasticity and behaviour under magnetic fields of cubic lyomesophases and smectic D liquid crystals

“…The cubic lyomesophases have a close analogue in the range of thermotropic liquid crystals, namely the so-called smectic D liquid crystal phases [8,10] which are not layered at all but also cubic as has been shown by polarizing microscopy [8,10] and in X-ray diffraction [11,12]. As with the cubic lyomesophases, the size of the smectic D unit cell is about 100 A and it contains of the order of 103 molecules.…”