Luminescent calix[4]arene macrocycles bearing coumarin arms for liquid crystal, aggregation-induced emission, and...

This study presents a new approach for the synthesis of blue light-emitting macrocyclic compounds (C4CA1-C4CA4) using the induction of functionalized coumarin units with variable alkyl arms at the narrow edge of the calix[4]arene rigid core. All four macrocyclic compounds adopted cone conformation, as supported by ¹H NMR and DFT study. All four macrocycles exhibit nematic type liquid crystalline behavior with a broad temperature range. The structures of the macrocycles were confirmed by FT-IR spectroscopy, ¹H and ¹³C NMR spectroscopy, MALDI-TOF mass spectrometry, and elemental analysis. A detailed structure-property relationship reveals how the variations in terminal substituents affect the mesomorphic properties of the macrocycles with their temperature range and thermal stability. All four macrocycles exhibit good quantum yield with aggregation-induced emission behavior. Among the series, a selected compound (C4CA4) was tested for nematode imaging study in both solution and aggregated state conditions. The results highlight calix[4]arene-functionalized coumarin frameworks with fluorescent liquid crystalline nature, attributed to their thermally stable mesophases and favorable optical properties, making them promising candidates for bioimaging applications.