New chiral dimers consisting of a rod‐like and cholesterol mesogenic units are reported to form a chiral twist‐bend nematicphase (NTB*) with heliconical structure. The compressibility of the NTBphase made of bent dimers was found to be as large as in smectic phases, which is consistent with the nanoperiodic structure of the NTBphase. The atomic force microscopy observations in chiral bent dimers
This paper presents results of our studies of a full homologous series of 4-(4′-alkyloxyphenylazo)benzoyl chlorides. Until now these compounds have been used only as intermediates for more complex materials and their properties were not investigated as acid chlorides are considered unstable and hence useless for applications. We show that they are in fact quite durable and possess liquid-crystalline
We present a series of small-molecular trisazobenzene chromophores, including, for instance, 1,3,5-tris[4-[4-[(4-cyanophenyl)azo]phenoxy)butyryl]amino}benzene that feature a remarkably stable light-induced orientation in initially amorphous thin-film architectures. It is demonstrated that for optimal performance it is critical to design chemical structures that allow formation of both an amorphous and a liquid-crystalline phase. In the present approach, the liquid-crystal line feature was introduced by inserting decoupling spacers between a trisfunctionalized benzene core and the three azobenzene moieties, as well as adding polar end groups to the latter. To compensate for the deleterious reduction of the glass transition temperature associated with the spacers in the compounds, polar units were incorporated between the benzene core and the side groups. Intriguingly, the molecular glasses that feature a latent liquid-crystal line phase display a remarkable "postdevelopment", i.e., an increase of the amplitude of refractive index modulation in holographic experiments after writing of optical gratings is arrested, exceeding 20% for the previously mentioned derivative. Thus, these nonpolymeric, azobenzene-containing compounds presented in this work appear to be attractive candidates for fabrication of stable holographic volume gratings.
Muxfeldt,H. et al., Chemische Berichte, 1965, vol. 98, p. 3040 - 3044