Investigation of supramolecular architectures of bent-shaped pyridine derivatives: from a three-ring crystalline compound towards five-ring mesogens

TL;DR

This study explores the synthesis and mesomorphic behavior of five-ring pyridine-based bent-core compounds with various substituents, revealing how different groups influence liquid crystal properties and potential UV indicator applications.

Contribution

It introduces new five-ring pyridine derivatives and compares their mesomorphic properties with three-ring compounds, advancing understanding of molecular design for UV-responsive liquid crystals.

Findings

Methoxy groups suppress mesomorphism.

Chloro- and nitro-substituted compounds form B1-like phases.

UV light alters mesophase textures and transition temperatures.

Abstract

In searching for novel photoactive liquid crystals, we have synthesized a series of five-ring pyridine-based bent-core compounds bearing different substituents at the peripheral phenyl rings (CH3O, Cl and NO2). Their mesomorphic behaviour has been investigated by polarizing optical microscopy, differential scanning calorimetry and X-ray scattering, and then compared with the unsubstituted parent compound. The introduction of the methoxy groups at the peripheral phenyl rings of the bent core results in a non-mesomorphic compound, whereas the chloro- and nitro-substituted compounds form enantiotropic B1-like phases. Significant changes of the textures and transition temperatures of the mesophase have been observed under UV light. The presented investigation of the mesomorphic properties of the synthesized compounds, coupled with analysis of the molecular packing of the related three-ring compounds, will help to design self-organized molecules suitable for UV indicators.