Molecular recognition of Atrazine, 2,4-Dichlorophenoxyacetic acid, and Chlorpyrifos by cyclodextrin-based adsorbents: insights into selective pesticide removal

Cyclodextrin (CD)-based host–guest complexation represents an effective supramolecular approach for the selective capture of pesticide contaminants. In this study, the binding behavior of Atrazine, 2,4-Dichlorophenoxyacetic acid (2,4-D), and Chlorpyrifos with α-, β-, and γ-CDs was evaluated comparatively using molecular docking and interaction analysis. The results revealed that the balance between molecular size, polarity, cavity compatibility, and interaction diversity strongly governs pesticide affinity. Among the studied systems, β-CD showed the most favorable and versatile performance, particularly for Atrazine and 2,4-D, where its intermediate cavity size enabled balanced rim anchoring and hydrophobic inclusion. Atrazine was stabilized mainly through hydrogen bonding and distributed weak interactions, while 2,4-D benefited from carboxylate-mediated rim anchoring combined with partial cavity fitting. For Chlorpyrifos, the larger γ-CD cavity provided the strongest accommodation due to the bulky and hydrophobic nature of the molecule, supported by hydrogen bonding, carbon–hydrogen bonding, van der Waals contacts, and a distinctive π–sigma interaction. In contrast, α-CD mainly promoted rim-dominated binding because of its restricted cavity, whereas γ-CD showed loose-fit behavior for smaller pesticides. Overall, the findings indicate that β-CD is the most broadly applicable host, while γ-CD is especially suitable for bulky chlorinated pesticides. These molecular-level predictions provide a basis for prioritizing CD–pesticide combinations for further experimental validation and the subsequent development of CD-based remediation materials.