Thermotropic liquid crystals fromN-alkylpyridinium halides ω-substituted with a mesogenic group

Effect of smectogenicity of the ionic groups on the thermotropic liquid crystalline behavior of pyridinium and poly(4-vinylpyridinium) salts quaternized with mesogenic groups

“…12 It is worthwhile to remark that, in spite of the presence the cyano and chiral groups, the proposed arrangement is exactly the same as that observed with (methoxybiphenyl)pyridinium halides. 6 This result clearly demonstrates the strong power of the ionic functions. They impose the smectic monolayer organization although the cy-…”

“…This particular organization may be explained by the presence of pected for the lateral packing area of rodlike smectogenic molecules. 15 They indicate that, in the chiral chain on the mesogenic part which would disturb the structure, when comparing to these layers, there are two molecules per unit cell, one at the center and the other at the vertices Navarro's study, who had observed a sharp Bragg reflection in the wide-angle region with the mewith respect to the chevron structure as described by Navarro et al 6 for (methoxybiphenyl)pyridinthoxybiphenyl mesogen. This result clearly indicates two antagonist structural behaviors; the ium halides.…”

“…1,2 More recently, with various analogous monomers. 6 They constiionic LC polymers were also obtained by quaternization of pyridine groups attached to a polymeth-leads to LC properties only after quaternization. 4,5 sulting in the formation of a 4-hydroxy-4-(2-methylbutoxy)biphenyl, which was then treated In all the cases, only smectic phases were observed in which the mesogenic pendant groups with a,v-alkyl dibromide yielding the desired alkyl bromide.…”

Thermotropic liquid crystalline behaviour of pyridinium and poly(4-vinylpyridinium) salts quaternized withω-alkyl phenylbenzoate derivatives

“…Then the alkyl spacer (6 or 12 methylene units) is added in a second step by reaction, in small excess, of dibromohexane or dibromododecane, respectively, with 4-methoxyphenyl 49-hydroxybenzoate. The pyridinium salts were finally obtained by quaternisation of pyridine by the alkyl bromide derivatives in the same conditions as already described 6) . The use of pyridine as solvent and reactant avoids side reactions that occur with polar solvents such as DMF and methanol.…”

Thermal Behavior of Dodecylpyridinium-Based Surfactant Salts with Varied Anionic Constituent

“…Three types of mesophases, smectic A, B and E were identified in N-alkylpyridinium halides substituted with a 4-methoxybiphenoxy group, with the individual molecules laterally arranged head to tail, bringing the anion close to positively charged pyridinium rings. 37,38 The similar structures with interdigitated molecules and sandwiched anions between pyridinium rings were described for the smectic A phase of 4-methyl-N-alkylpyridinium halides 39 and N-methyl-4-alkylpyridinium iodides. 36 Unlike these results, dodecylpyridinium chloride shows quite different type of LC mesophase.…”