New columnar liquid crystals Correlation between molecular structure and mesomorphic behaviour

Abstract

The effect of molecular structural changes on the mesomorphic nature of a new class of macrocyclic columnar liquid crystal is reported. Twenty-six new compounds with general molecular structure I were prepared, characterized and compared.Only dodecasubstituted ester derivatives 2d-h exhibit thermotropic mesophases. The design of mesogens based on these new, unusual macrocyclic cores requires the presence of the following structural elements: twelve aliphatic side chains, esters as bridging units and small R groups on the core.

Chemistry of calix[4]resorcinarenes

“…261 Ð The groups R 1 are small (e.g., in compounds 89a,b, maximum R 1 = CH 3 ), which allows an optimal core stacking.…”

A new, conformationally mobile macrocyclic core for bowl-shaped columnar liquid crystals

“…A correlation between the thickness of the core and the length of the side chains is established, which shows the high sensitivity of this system towards the thickness of the macrocyclic moiety [7]. The mesophase structure also changes from uniaxial D,, (2) to biaxial D, (1) with a chevron organization in the ah plane.…”

“…Among others, columnar bowl-shaped compounds, based on the rigid cyclotriveratrylene core, are particularly interesting for their novel supramolecular organization Recently we have introduced a new class of mesogens, consisting of bowl-shaped metacyclophane core symmetrically surrounded by twelve alkyl chains (2, figure 1) [6,7]. Now we report the preparation, physico-chemical characterization and mesomorphic properties of a related class of bowl-shaped columnar liquid crystals (1).…”

Microscopic Heterogeneity in a Bowlic Columnar Mesophase as Probed with Fluorescence Depolarization Measurements

“…1 ,dDiphenyl-l, 3 (DPH) and dichloromethane (HPLC grade) were obtained from Aldrich and used as supplied.…”