Several rodlike 4,4‘‘-bis(decyloxy)-p-terphenyl derivatives incorporating nonionic hydrophilic groups in the lateral 2‘-position (2-oxa-4,5-dihydroxypentyl, 2,5-dioxa-7,8-dihydroxyoctyl, 2,5,8-trioxa-10,11-dihydroxyundecyl, and 2,5,8,11-tetraoxa-13,14-tetradecyl groups) and 2‘-(2-oxa-4,5-dihydroxypentyl)-4,4‘‘-diundecyl-p-terphenyl form well-ordered thin films when spread at the air−water interface. One observes two sharp breaks in the pressure/area isotherms separated by a large plateau. The first break occurs at an area of ca. 0.90 nm2/molecule, an area which corresponds to a side-on arrangement of the terphenyl units at the interface. The plateau corresponds to a first-order phase transition. The surface pressure related to this transition significantly rises with an increasing number of oxyethylene units in the hydrophilic lateral groups. Brewster angle microscopic investigations indicate the formation of fluid domains in this region. In some cases these domains coalesce to a homogenous layer. The surface potential is nearly constant in the region of the plateau, which can be explained by a defined collapse due to the formation of a triple layer consisting of a bilayer on top of the monolayer.

The lateral fixing of calamitic mesogens through hydrogen bonding of facial amphiphiles is a novel way of generating smectic materials with a broad mesomorphic region. Compound 1 is an example of this amphiphile and represents a new type of liquid‐crystalline carbohydrate. R = OC10H21.

The influence of water, formamide, and n-dodecane on the liquid crystalline properties of several rodlike 4,4′′-bis(decyloxy)-p-terphenyl derivatives incorporating nonionic hydrophilic groups in a central position was investigated by polarizing microscopy and X-ray scattering. Up to three different rectangular columnar mesophases have been found for molecules with large hydrophilic groups with increasing concentrations of protic solvents. Remarkably only one lattice parameter changes in dependence on the mesophase type and the number of solvent molecules coordinated to the polar groups. We propose that the columns represent ribbons consisting of the rigid terphenyl units, separated laterally by the segregated regions of the hydrophilic groups, whereby the three different columnar mesophases should result from an anisotropic swelling of the polar regions on addition of solvents. Lipophilic solvents (dodecane) destabilize the columnar phases and replace them by smectic layer structures (S A phases).

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Three 4,4′′-didecyloxy-p-terphenyl derivatives with laterally attached crown ether units of different ring size [(1,4,7,10-tetraoxacyclododecyl)-, (1,4,7,10,13-pentaoxacyclopentadecyl)-, and (1,4,7,10,13,16-hexaoxacyclooctadecyl)-2-methyl 2,5-bis(4-decyloxyphenyl)benzoate] have been synthesized, and their Langmuir films were investigated by means of a film balance. They form well-ordered thin films when spread at the air-water interface which are characterized by two sharp breaks in their surface pressure-area isotherms separated by a large plateau. The lateral pressure in the plateau regionsin which the molecules undergo a first-order phase transition with formation of a defined triple layerssignificantly increases on enhancing the number of oxyethylene units in the crown ether units. Additionally, it depends on the type and concentration of alkali metal ions (Li + , Na + , K + , Rb + , Cs + ) in the subphase. Cations which fit the cavity of the appended crown ethers most significantly stabilize the films. It seems that the surface pressure in the plateau region is reminiscent of the binding constants of alkali metal ions to the crown ether units. This shows that facial amphiphiles could represent an interesting new platform for the investigation of guest-host interactions and molecular recognition processes at the air-water interface.