Thiourea derivatives acting as functional monomers of As(Ш) molecular imprinted polymers: A theoretical and experimental study on binding mechanisms

Abstract

Thiourea derivatives are expected to be potential monomers of As(Ш) molecular imprinted polymers (MIPs) which are used to specifically recognize As(Ш). However, the specific recognition and binding mechanisms between template and monomers are unclear, which limits the practical applications of MIPs in As(Ш)detection. In this work, density functional theory (DFT) calculations, molecular dynamics (MD) simulations and experimental methods were jointly applied to explore the binding interactions between H₃AsO₃ and thiourea derivatives and environmental factors influences, aiming to find out the best monomer and optimal preparation conditions for H₃AsO₃ MIPs. Among five monomer candidates, (2, 6-difluorophenyl) thiourea (FT) was calculated to be the most potential one, while allyl thiourea (AT) was the second choice. Configurations of the most stable binding complexes were found out. The optimal solvent was found to be toluene and the bindings were more favorable at pH 7.5 in aqueous solution. Besides, EGDMA was proved as the best cross-linker with the optimal ratio of template: monomer: cross-linker= 2:3:20. Moreover, the binding interactions were identified to be hydrogen bonds, and the non-covalent nature was revealed. These findings provide references for efficient design and preparation of good-performance H₃AsO₃ MIPs, which can be used to detect and remove As(Ш) from environment.

Keywords: Binding mechanisms; H(3)AsO(3); Hydrogen bonds; Theoretical study; Thiourea derivatives.