Design and synthesis of fluorescent calix[4]arene-1,8-Naphthalimide derivatives: Transparent biofilms, antioxidant and antimicrobial properties, and real-samples applications

Recent advances in materials science have underscored the role of supramolecular architectures in antimicrobial system design. Calix[4]arene-based systems have gained attention due to their structural versatility, fluorescence, and applicability in antimicrobial and food-packaging applications. Here, fluorescent calix[4]arene–naphthylimide derivatives were synthesized and subsequently functionalized with three different piperazine derivatives to introduce antimicrobial activity, yielding novel fluorescent calix[4]arene–piperazine derivatives (5,6, and 7). The antioxidant activities of these compounds were evaluated using the DPPH radical scavenging assay. Antimicrobial transparent biofilms (HA-5, HA-6, and HA-7) were then fabricated by interacting 5, 6, and 7 with hyaluronic acid (HA). Among these materials, HA-7 exhibited the most potent antimicrobial activity against Sarcina lutea , with a minimum inhibitory concentration (MIC) of 0.097 mg/mL. Owing to its high transparency and strong antimicrobial performance, HA-7 was further evaluated as a food-packaging material for strawberries and sour mulberries, where it effectively extended the shelf life of these fruits.