Glass forming banana-shaped compounds: Vitrified liquid crystal states

Abstract

The synthesis and physical properties, in particular electro-optic switching behavior, of 3-chloro-biphenyl-3',4-bis[4-[4-(3,7-dimethyloctyloxy)-phenyliminomethyl]] benzoate are reported. The compound exhibits an antiferroelectric tilted smectic liquid crystalline phase (Sm-CP) in a broad temperature range. Below 20 degrees C the sample goes over to a glassy state and no crystallization appears down to -50 degrees C. It is observed that below the glass transition temperature both achiral and chiral structures of the Sm-CP phase can be frozen. Each of them can have three polarization states (two ferroelectric and one antiferroelectric), thus giving six different vitrified textures. This enables atomic force microscopy studies of the different liquid crystalline states and suggests possibilities for electro-optical storage devices.

Incorporation in Langmuir and Langmuir–Blodgett films of symmetric fluorine substituted bent-core liquid crystals: Morphological and optical properties

“…Thus, according to the MakerFringes method, angle dependent SHG-measurements were performed for mono-and multilayer LB-structures implementing both significant P-In/P-Out and S-In/P-Out laser beam polarization geometries as explained before. The estimated NLO-coefficients are in good agreement with those reported in the literature for bent-shaped compounds composed of several benzene rings [5,18,[34][35][36][37][38][39][40].…”

POLAR MICRO STRUCTURES OF THE B2- AND B4-PHASES OF BENT-SHAPED LC-MOLECULES RESOLVED BY NONLINEAR OPTICAL MICROSCOPY

“…These molecular structures have been reported in the literature. 4,12,14,17,18 The different phase transitions have been determined by polarizing microscopy and differential scanning calorimetry (DSC).…”

Electrically Tunable Color by Using Mixtures of Bent‐Core and Rod‐Shaped Molecules

“…Mixtures of bent-core and rod-shaped molecules have shown interesting properties, such as enhancement of the chirality in cholesterics, [10,11] induction of antiferroelectric order in smectics, [12,13] or a complete miscibility of smectic bent-core and nematic rod-shape substances. [14,15] Although there are few examples in which bent-core materials do not crystallize at room temperature, [16,17] they are glassy and could not be switched at room temperature. Here we show that by mixing suitable bent and rod-shape molecules one can form fluid liquid crystals at room temperature that change birefringence color at electric fields, thus opening up a path towards possible practical applications.…”