Introducing the azocinnamic acid scaffold into bent-core liquid crystal design: A structure–property relationship study

Autor: Kristina Gak Simić, Paulina Rybak, Damian Pociecha, Luka Cmok, Irena Drevenšek-Olenik, Tibor Tóth-Katona, Nemanja Trišović
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Journal of Molecular Liquids
Popis: A series of bent-core liquid crystals possessing the azocinnamoyl unit in both elongating side arms was synthesized. The chain length was kept fixed for each molecule (C12H25), whereas the substituents at the central and outer rings were varied. The LC phases were assigned by polarizing optical microscopy, differential scanning calorimetry and X-ray diffraction. The investigated compounds are suitably diverse to reveal some aspects of the relationship between molecular structure and the mesomorphic properties. Namely, non-substituted parent compound is crystalline only and the methyl group in position 2 or the chlorine atom in position 4 of the central ring suppresses LC phase formation. Introduction of the strong electron-withdrawing nitro group between the side arms on the central ring leads to a B7 phase. Compounds possessing a bromine atom or two chlorine atoms in the neighbourhood of the ester groups form LC phases typical for rod-like molecules, namely a nematic – smectic phase sequence. The results are compared with those reported for the azobenzoyl analogues.
Databáze: OpenAIRE