Asymmetrical liquid crystal dimers with 1,2,3-triazole bent-mesogenic core: synthesis, characterization and theoretical studies

Abstract

This work reports new liquid crystal dimers containing an alkoxy spacer that connects 1,4-disubstituted triazole-bent core with a rod-like esterified biphenyl mesogenic core and a Schiff base with terminal cyanobiphenyl group. The structures of these dimers were elucidated using spectroscopic techniques, while optical and thermal properties were obtained using POM and DSC. All compounds exhibited monotropic nematic Schlieren textures upon cooling. Compound with OC10H20 changed from a stable nematic phase to a smectic C phase which can be attributed to its precise orientation and trans-conformational molecular architecture. The length of the OCnH2n spacer affected the mesophases and phase transition temperatures, revealing a pronounced odd-even effect. An apparent reversal of the conventional odd-even trend was observed when the ether oxygen atom contributes to the effective spacer parity. Further analysis using DFT confirms the impact of structural conformation and dipole moments on the nematogenic and smectogenic properties of bent-core liquid crystals (BCLCs).