Experimental and Theoretical Studies on the Inclusion Process of the Benzoxazolinone in β-Cyclodextrin

Spectroscopic investigation supported by molecular modeling methods has been used to describe the inclusion complex of β-cyclodextrin (β-CD) with Benzoxazolinone in solution and in solid state. By using UV-Vis absorption, the stoichiometric ratio of the complex was found to be 1 : 1 and the stability constant was evaluated as 410 000 (mol/L)^–1. Solid state characterization by FT-IR spectroscopy provided remarkable evidences of the formation of inclusion system. Moreover, semi-empirical calculations using PM3 level of theory and hybrid method ONIOM2 clearly indicate that the formed complexes are energetically favored in vacuum and in solution. Semi-empirical calculations using PM3, ONIOM2 (B3LYP/6-31G(p,d): PM3) methods, in vacuum and in acetonitrile were performed. The negative energy values obtained demonstrate clearly that the benzoxazolinone molecule can form a stable inclusion complex with β‑CD and the B orientation is significantly more favorable than the A orientation. From NBO analysis, the mutual interactions between β-CD and BOA were analyzed and discussed.