[2]Benzothiophene bent-shaped liquid crystals

Abstract

New liquid crystalline (LC) compounds containing the [2]benzothiophene chromophore unit have been synthesised and their mesomorphic properties studied. Mesomorphic and fluorescent properties have been modified by various chemical moieties. Among others, terminal fluoroalkyl and/or chiral chains were introduced to stabilise mesophases and support the formation of polar phases. In spite of the bent shape due to the central 1,3-diphenylbenzo[c]thiophene unit, all compounds exhibit phases typical for the rod-like LC: nematic, smectic A and smectic C or their chiral analogues using the chiral (S)-C 2 H 5 CH(CH 3 )(CH 2 ) 6 CO or (S)-C 10 H 21 OCH(CH 3 )CO chain. The orientational order in the nematic phase was studied by polarised infrared measurements. The fluorescent properties of the studied compounds have been measured and their parameters established.

Chemical Structures, Mesogenic Properties, and Synthesis of Liquid Crystals with Bent‐Core Structures

“…For example, the bend angle afforded by [2]-benzothiophene materials [29] is too large and prevents the compact packing that is typical of bent-core liquid crystals. This gives rise to materials that only form calamitic phases.…”

“…On the other hand, the thermal and radical photopolymerization was carried out for 1,3-dienoxy bent-core monomers (28). [79d] The in situ photopolymerization of the SmCP phase of biphenyl-based acrylates or methacrylates, afforded free-films that retained the SmCP-like order at room temperature (29). [114b] In contrast, nematic or columnar mesomorphism was reported for a series of ladder-type polyethers depending on the substituents attached to the central phenyl ring of the bent-core monomer (30).…”