Abstract
Unsymmetrical benzo[15]crown‐5 ethers 5 with one lateral ortho‐terphenyl unit bearing alkoxy side chains of varying chain lengths (C5–C14) were prepared from 3,4‐dialkoxyphenylbromides 2. Complexation with metal salts MX (M = Na, Cs) afforded the corresponding derivatives MX**⋅5**. The uncomplexed crown ethers 5 h and 5 i, with dodecyloxy and tetradecyloxy side chains, respectively, exhibit liquid crystalline properties. In the series of complexed crown ethers, liquid crystal properties appeared as early as NaI**⋅5 f** with C~9~H~19~ side chains. Whereas the uncomplexed 5 h,i form smectic mesophases, the complexed NaI**⋅5 g** and NaI**⋅5 h** exhibit textures typical of columnar mesophases. These results were supported by X‐ray diffraction measurements (WAXS, SAXS), which revealed smectic (5 h,i), rectangular columnar (NaI**⋅5 g**), and hexagonal columnar (NaI**⋅5 h**) mesophases. As the liquid crystalline phase might retain packing features of the solid‐state structure, single‐crystal X‐ray analyses were also performed for some of the uncomplexed and complexed crown ether derivatives. The complex NaI~3~⋅5 a displays a sandwich‐type structure, with the crown ether cores mutually antiperiplanar and maintaining an almost perfect crown conformation. In contrast, non‐mesogenic uncomplexed crown ether 5 b displays a layer‐type ordering in the solid phase.