Liquid crystalline materials with a chiral part based on lactic acid have been intensively studied for the last decades due to their rich liquid crystalline properties attractive for potential applications but also due to a reasonably low synthetic costs. The main mechanisms to reach the desirable liquid crystalline properties are: (i) tuning the molecular architecture, specifically changing the type and the structure of the molecular core, length of the terminal chains, type and the position of the lateral substituents, (ii) attaching different polymerisable groups for further design of the macromolecular materials that increase the stability of the system and (iii) incorporation of various functional groups (like photosensitive azo group, etc.) in the molecular core. However, it is still almost impossible to achieve the desired properties for a pure single liquid crystalline compound. Mixing of structurally similar or structurally different materials is a powerful tool for tuning the properties of the resulting mixture. This presentation will be devoted to the results obtained on a large variety of lactic acid derivatives of different molecular architecture. Uncommon mesophases and their properties will be highlighted and a potential usefulness of such materials will be discussed.

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Liquid crystal has been categorized based on the anisotropic shape of mesogenic molecule to give two types of liquid crystals such as calamitics (rod-like) and discotics (disc-like). Recently a novel and unique liquid crystalline property was found for hexa-tetradecyloxyazobenzene-substituted triphenylenes (1-C14) which exhibits a bimesomorphism of calamitic (smectic) and discotic (columnar) liquid crystalline phases in both thermotropic and photo-induced isothermal conditions and these should be accompanied with change of molecular anisotropic shape between rod and disc1. The phase transitions of the alkyl homologues (1-C11- 1-C16) also exhibit just the same manner in their mesomorphism,2 though different properties of phase transition parameters and phase sequences. In this communication, phase transitions of the alkyl homologues in both thermotropic and photonic process are shown and the phase transition mechanism is discussed.

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Despite of recent development in optical-sensitive devices fabricated in various field of industries, such as new emerging blue light-emitting diodes LEDs, optically active chalcone-based material continues to be a promising mesogen. The reasons of this perspective include the versatility of organic synthetic chalcone materials and their nonlinear optical (NLO) property. Herein, we report a new homologous series of non-symmetric liquid crystal dimer in which a thiomethyl-substituted chalcone core unit is covalently tethered to a nitro-substituted Schiff base core unit through an odd-even parity alkyl spacer, -(CH2)n-, with n ranging from 2 to 4, 6, 8, 10, and 12. The molecular structure of title compounds are confirmed using IR, NMR and EI-MS spectrometric techniques. The mesomorphic properties were studied using differential scanning calorimetry and polarized optical microscopy. It is note-worthy that the even-membered homologues (where n = 2, 4, 6, 8, 10, 12) stabilize monotropic nematic phase solely, which is rather surprising given that its odd-membered homologues (where n = 3, 5) has non-mesomorphic properties due to their bent-shaped molecular packing.

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