Crucial Role of the Tropone C=O Group in Preferential Exhibition of Smectic C Phase through Intermolecular Hydrogen Bonding

Abstract

New 5-alkoxy-2-(4-alkylaminobenzoyloxy)tropones showing a smectic C phase exclusively were prepared. The corresponding benzenoids were non-mesogenic. The variable-temperature FT-IR spectra of 2-(4-dodecylaminobenzoyloxy)-5-tetradecyloxytropone suggested the intermolecular hydrogen bonding between the NH and both the tropone and the ester C=O groups in the mesophase.

Generation of Stable Calamitic Liquid-Crystal Phases with Lateral Intermolecular Hydrogen Bonding

“…In mesophases, hydrogen bonding is effective for organizing highly ordered suprastructures. − In preceding papers, dimers 2 and molecular networks 3-5 were reported in liquid-crystal phases of rodlike molecules possessing a hydrogen-bonding site at their terminals. The directions of their intermolecular hydrogen bondings are parallel to their long axes.…”

A new series of liquid‐crystalline bi‐1,3,4‐oxadiazole derivatives: synthesis and mesomorphic behaviour

“…This is due to an increasing microphase segregation effect arising from the enhanced incompatibility between the rigid aromatic rings and flexible alkoxy chains with increasing terminal chain length. Such a microsegregation effect was considered to be the driving force for the formation of the smectic phase (18,19). The high stability of either the smectic C or nematic phase of BBOXD-n, indicated the presence of strong intermolecular interaction which might have stabilised the parallel alignment of molecules (20)(21)(22)(23)(24).…”

Synthesis and thermotropic behaviour of imidazole-terminated liquid crystals

“…Imi-DAH contains a rigid diacylhydrazine core, a long-chain hydrocarbon spacer and a terminal imidazole group. Lateral hydrogen bonding between diacylhydrazine cores is expected to support parallel alignment and stabilise smectic mesophases [16][17][18][19]. The core is connected to a long, tetradecane spacer to further promote high-temperature ordered phases and also to decouple the motion of the imidazole end-group from the ordered cores.…”