On the Investigation of Encapsulation Behavior of Cucurbit[6]uril With Aspirin

ABSTRACT This study examines the inclusion and interaction behavior of cucurbit[6]uril (CB[6]) with acetylsalicylic acid (ASA), a widely used nonsteroidal anti‐inflammatory drug. A solid inclusion complex of CB[6]‐ASA was prepared by a co‐precipitation process and characterized by ATR/FT‐IR, XRD, 1 HNMR, 13 C CP/MAS NMR, HRMS, and TGA. Nonlinear global fitting and additional Job's plot methods indicate 1:1 stoichiometry. Density functional theory (DFT) calculations provide further evidence of a 1:1 inclusion complex. The inclusion complex exhibited high interactive behavior, with binding constants in the range of 171–350 M −1 , as determined via concentration‐dependent UV‐vis and fluorescence spectroscopic titration methods, suggesting an equimolar complex. ASA encapsulation transpires via a distorted CB[6] cavity with the phenyl moiety of the guest.