Selective Host–Guest Complexation of Local Anesthetic Ester‐Type Caine Drugs with Pagoda5arene: Fluorescence Response and Structural Analysis

The complexation behaviors between four local anesthetics and pagoda5arene were investigated using 1 H NMR spectroscopy, fluorescence spectroscopy, and density functional theory calculations. Among the four selected local anesthetics, only tetracaine and procaine were found to form stable 1:1 host–guest complexes with pagoda5arene. Structural analyses revealed that the alkylammonium moieties of these two ester‐type anesthetic guest molecules could be encapsulated within the electron‐rich cavity of pagoda5arene. The stability of the resulting complexes arises from the synergistic contributions of multiple noncovalent interactions, including C–H··· π interactions, π ··· π interactions, and hydrogen bonding. This selective binding behavior provides new practical opportunities for applications in pharmaceutical analysis, clinical safety monitoring, and drug quality control.