Amide-linked luminescent polycatenar liquid crystals: tuning self-assembly and optical properties via diphenylnaphthalene versus diphenylbutadiyne cores

Two symmetric polycatenar were rationally designed by employing diphenylbutadiyne (AA) or diphenylnaphthalene (NA) as the central core, capped with trialkyloxybenzyl terminals via amide linkages. Both compounds can self-assemble into hexagonal columnar phases (Colhex/p6mm) with negative birefringence but exhibit distinct supramolecular functionalities rooted in their core structures. The compound AA, featuring a linear diphenylbutadiyne core, demonstrates unique photoresponsive behaviours and forms stable gels exclusively in specific solvents. Its organogel undergoes irreversible collapse accompanied by blue-to-yellow emission transition upon UV irradiation (365 nm), showing potentials as a stimuli-responsive material for security labels. In contrast, the compound NA, with a twisted diphenylnaphthalene core, displays broad gel properties and acts as a highly selective and sensitive fluorescent sensor for H2PO4− anions via a modulated excited-state proton transfer process with a detection limit of 27 nM.