Cucurbit[ <i>n</i> ]urils‐Mediated Structural Regulation of AIE Supramolecular Assemblies and D–π–A Structure‐Driven Ion Recognition and Selective Cytotoxicity Applications

ABSTRACT The precise control of supramolecular assembly to achieve multifunctional integration remains a significant challenge in materials science. In this study, we synthesized a novel, previously unreported AIE‐active molecule (BA) through an exceptionally simple procedure. Subsequently, we constructed two cucurbituril‐mediated assemblies (Q[8]‐BA and Q[10]‐BA) using BA as the building block. These assemblies were systematically investigated for their differences in ion recognition, cellular imaging, and cytotoxicity. The Q[8]‐BA assembly exhibited enhanced fluorescence intensity, pH sensitivity, and high specificity for Co 2+ detection (LOD = 4.8 × 10 −7 M), making it a promising candidate for environmental sensing and cell imaging. In contrast, the Q[10]‐BA assembly demonstrated selective cytotoxicity toward melanoma cells while protecting normal cells, highlighting its potential in cancer theranostics. These findings reveal the critical role of cavity size and assembly mode in regulating material properties, providing new insights for designing multifunctional supramolecular systems with tailored functionalities for environmental monitoring and biomedical applications.