A novel approach to construct a calix[4]arene-appended rhodamine B-based supramolecular system for nematic mesophase and nematode cell imaging

Abstract

A novel supramolecular system based on calix[4]arene linked with rhodamine B was designed and synthesized, incorporating different alkoxy side chains. All four supramolecular compounds (3a–3d) synthesized using this approach exhibited nematic-type liquid crystalline properties. Detailed analyses using polarizing optical microscopy, differential scanning calorimetry, the X-ray diffraction technique, and thermogravimetry were performed to investigate the microscopic, molecular arrangement pattern, and thermal behavior of the compounds. The well-known Schlieren and threaded-type texture pattern was observed in all four bi-substituted calixarene derivatives. They displayed unique texture patterns supporting the idea of a well-organized supramolecular structure. Additionally, these materials demonstrated enantiotropy-type mesophase with a wide temperature range and good thermal stability. Notably, they exhibited light-emitting properties in both solution and solid thin film states, showing the intriguing aggregation-induced emission effect. All four compounds adopted a cone conformation with two side substitution on the calix[4]arene rigid core. Compound 3c was utilized to stain nematode samples using a solution-state aggregation approach. The fluorescent supramolecule effectively allowed visualization and tracking of the staining patterns within the nematode organisms. This methodology enabled the examination of cellular and subcellular structures, further offering valuable insights into the behavior and morphology of nematodes.