A Theoretical Study of Clorsulon-Imprinted Polypyrrole: Modeling Complementary Cavity Formation and Rebinding of Clorsulon

Clorsulon is highly toxic to aquatic organisms, including fish and invertebrates, and can have long-term adverse effects on the environment. It is commonly used in cattle, and residues excreted in dung can negatively affect dung-dependent insects. Direct contamination of waterways, such as ponds, streams, or ditches, should be strictly avoided. Therefore, clorsulon detection is pivotal. In this study, density functional theory (DFT) and semiempirical metadynamics are used to investigate the properties of polypyrrole-based molecularly imprinted polymer (MIP-PPy) as a receptor targeting clorsulon detection. To address this aim, the electronic and physicochemical properties of PPy are studied, and the optimal imprinting conditions are calculated. The novelty of this study lies in the in silico characterization of the effects of PPy conformers on its electrochemical properties under different couplings. Next, the sensing mechanism via binding sites formed in the modeled imprinted polymer is described. The ratio of pyrrole monomers needed to form the optimal imprinted PPy for clorsulon drug detection is determined, and the solvent effect is evaluated. A water-based solvent was selected as the best medium and solvent for preparing the polymerization mixture, since it does not interfere with the optimized monomers and template molecules at a 16:1 ratio. Moreover, the αβ- and ββ-coupling present in PPy chains was considered and compared with the ideal configuration of all αα-coupled chains. Finally, the sensing mechanism and electrochemical properties of the in silico-designed MIP-PPy are discussed.