Synthesis and Characterization of Tris-Methacrylated 3,4,5-Tris[(alkoxy)benzyloxy]benzoate Derivatives

Abstract

The synthesis of liquid crystalline 3,4,5-tris(11-methacryloylundecyl-1oxybenzyloxy)benzoic acid, 2-methyl-(1,4,7,10,13-pentaoxacyclopentadecane)-3,4,5tris[4-(11-methacryloylundecyl-1-oxy)benzyloxy] benzoate and its 1:1 complex with sodium triflate is described. The observed mesophases were identified, by polarized optical microscopy and contact preparation techniques, to be of hexagonal columnar disordered structure. The amphiphiles form lyotropic columnar phases in concentrated methacrylate solvents, while at low solute contents supramolecular organogels emerge.Keywords: amphiphiles´benzoateś crown compounds´mesophasesó rganogelators function at the tip of the wedge and have polymerizable groups at the rim. [6] As they assemble to a solid supramolecular column, the receptor groups stack along the cylinder axis, thus forming a potential transport channel.Since the polymerizable groups are located at the outer rim of the aggregates, each cylinder is surrounded by a coat of monomer units. If the cylinders assemble in solution, a gel is [a] Dr.

Columnar liquid crystals derived from crown ethers with two lateral ester-substitutedortho-terphenyl units: unexpected destabilisation of the mesophase by potassium iodide

“…2.1 Synthesis 2-(4 0 -Methoxymethoxyphenyl)-4,4,5,5-tetramethyl[1,3,2]-dioxaborolane (2) [28][29][30][31][32] and 4,4 0 ,5,5 0 -tetrabromodibenzo [18]crown-6 (3) [33] were prepared according to procedures described in the literature. Compounds 4, 5 and 7 presented were prepared following the synthesis shown in Scheme 2.…”

“…Upon complexation with alkali metal salts the thermotropic system was converted into a lyotropic system which displayed rectangular columnar mesophases. Cation complexation not only induced novel mesophases or stabilised existing mesophases as observed for azacrowns with lateral ester groups [12], for oligophenylene vinylene benzocrown ether conjugates [15], or for taper-shaped crown ethers with gallic esters forming supramolecular channels [16][17][18][19][20][21], but even tuned the helicity of fibres made from chiral crown ether-substituted phthalocyanines as was published by Nolte and co-workers [22,23]. NaI complexes of unsymmetrical benzo [15]crown-5 ethers with one peripheral propeller-shaped ortho-terphenyl unit and four alkoxy side chains yielded columnar mesophases with a higher stability as compared to the corresponding salt-free systems [24].…”

“…On the other hand, a mesophase destabilisation by cation complexation was reported by He et al for calamitic liquid crystals bearing terminal crown ethers [25]. Previously symmetrical dibenzo [18]crown-6 ethers 1 with two peripheral orthoterphenyl units and eight alkoxy side chains were described which displayed hexagonal and rectangular columnar mesophases depending on the anion (Scheme 1) [26,27]. It was found that complexation with potassium salts possessing soft anions, e.g.…”

“…Besides complexation the polarity difference between the polar core unit and non-polar side chains may effect mesophase formation. In the symmetrical o-terphenyl-substituted dibenzo [18]crown-6 ethers 7 (Scheme 2) the core unit was extended and the weak polarity enhanced by the ester-linked gallic acid units together with the increased number of non-polar side chains. In order to gain a deeper understanding of the structure-property relationships of crown ether bearing thermotropic liquid crystals it was thus of interest to study both the influence of the gallic ester substituents and the metal ion complexation on the mesomorphic properties of derivatives 7.…”

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Gallic acid substituted ortho-terphenyl dimers linked by a central [18]crown-6 ether and their KI complexes were synthesised and characterised by differential scanning calorimetry, polarising optical microscopy and X-ray diffraction. With one exception, all salt free derivatives were liquid crystalline.

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