Abstract

Cyclodextrins have emerged as promising supramolecular platforms for the capture, stabilization, and controlled delivery of agrochemicals; however, detailed molecular information regarding their interactions with carbamate pesticides remains limited. Herein, the host-guest interaction between the pesticide carbaryl (CB) and beta-cyclo-dextrin (beta-CD) was investigated in aqueous solution through a combination of fluorescence spectroscopy, NMR spectroscopy, and theoretical calculations. Fluorescence titrations demonstrated the formation of a moderately stable inclusion complex, with a 1:1 binding model providing the best description of the experimental data and an association constant of 189 M-1. Structural characterization by NMR spectroscopy revealed selective interactions of the internal cavity protons of beta-CD upon complex formation. Additionally, intermolecular ROESY correlations provided direct evidence for the preferential inclusion of the naphthalene moiety of CB within the hydrophobic cavity of beta-CD, while the carbamate group remained located near the cyclodextrin rim. In parallel, DFT calculations further supported the experimentally proposed binding interaction and showed that stabilization of the complex is primarily governed by hydrophobic and dispersion-driven interactions involving the aromatic region of the pesticide. The combined experimental and theoretical results provide a detailed molecular description of CB recognition by beta-cyclodextrin and establish the structural basis of this host-guest system in aqueous media. These findings contribute to a deeper understanding of cyclodextrin-pesticide interactions and provide valuable molecular insights for the future development of cyclodextrin-based materials for pesticide sequestration, residue management, and environmental remediation applications.