Selective Host–Guest Complexation of Local Anesthetic Ester‐Type Caine Drugs with Pagoda[5]arene: Fluorescence Response and Structural Analysis

The complexation behaviors between four local anesthetics and pagoda[5]arene 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 pagoda[5]arene. Structural analyses revealed that the alkylammonium moieties of these two ester‐type anesthetic guest molecules could be encapsulated within the electron‐rich cavity of pagoda[5]arene. 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.