Crystal structures of long-chain alkane-α,ω-diols with an even number of carbon atoms from 20 to 24 are determined. The molecular structures are similar to those of the lower homologues with an even number of carbon atoms analyzed previously; however, the methylene chain packings are different from each other. In the newly analyzed structure, it is found that the crystal structure type has an advantage in the close packing for the methylene part with increasing hydrophobic interactions. Crystal structures of a different polymorphic form in the even number of carbon atoms from 16 to 24 are also determined. The molecular and crystal structures are similar to those of an odd number of carbon atoms analyzed previously. However, the structures are slightly different from self-assembled multilayer structures whose models are derived from a grazing incidence synchrotron X-ray diffraction data. The carbon number starting to exhibit a polymorphic form coincides with that starting to show a rotator phase which are observed just below their melting points. From the viewpoint of the epitaxial growth at the surface and of the calculated density, it is found that the crystal structure of the polymorphic form has an advantage in exhibiting the rotator phase.

In the title compound, C23H48O2, one of the hydroxy groups adopts a gauche conformation with respect to the hydro­carbon skeleton, whereas the other hydroxy group adopts a trans conformation. The mol­ecules form a layer structure similar to that found in the smectic A phase of liquid crystals. Inter‐ and intralayer hydrogen bonds are formed in the crystal. These features are similar to those of the homologues with an odd number of C atoms. The calculated density, however, deviates from that predicted by a relation between the density and the number of C atoms in alkane‐α,ω‐diols with an odd number of C atoms.

Symmetrical liquid crystalline dimers have been synthesised, composed of rod-like mesogenic units with polar groups and a siloxane core of varying length in the central region. All the dimers containing siloxane units have been shown to exhibit a smectic A phase, confirmed by polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Rheological properties under an applied electric field were investigated by rotational rheometer. The influence of the siloxane core length on rheological properties has been investigated, and in addition the behaviour of the liquid crystalline dimers in the smectic A phase under an applied electric field has been observed by POM.

Monohydrated single crystals of dioctadecyldimethylammonium chloride (DC 18 DA + Cl − ·H 2 O) were prepared and the crystal structure was determined to elucidate the effects of water molecules on the crystalline to liquid-crystalline phase transition behavior. From the observation during the phase transition of as-prepared single crystals by polarizing optical microscopy and powder X-ray diffractometry, we demonstrated that the water molecules are firstly melted with increasing temperature and one-dimensional ionic chains, [-{Cl (1 1 -5) planes. This rearrangement is accompanied by the formation of a smectic A like bilayer structure. In addition, the one-dimensional ionic chains are simultaneously stretched to the chain direction, and alkyl chains are interdigitated to reduce a free space within the hydrophobic unit. are merged into two-dimensional ionic layers by sliding on the

In the molecular structure of the title compound, C20H42S2, (I), the skeleton of the hydro­carbon has an all‐trans conformation. The terminal S—H bond is in a gauche conformation with respect to the skeleton. In the crystal structure, the mol­ecules are arranged along the c axis, the longest axis, forming layers in which the long axis of the mol­ecule is inclined to the layer plane. This packing is very similar to that of the smectic C structure of liquid crystals. Except for the length of the c axis, no big difference was observed between the crystal data obtained here and those of homologues with even numbers of C atoms already reported.