Effect of solvent on molecular recognition of molecularly imprinted polymer: experimental investigation and computational quantum chemistry analysis

Molecularly imprinted polymers(MIPs) for theophylline were synthesized using methacrylic acid as monomer, ethylene glycol dimethylacrylate as crosslinker, chloroform, tetrahydrofuran and dimethyl sulfoxide as individual solvent, respectively. The adsorption performance of the imprinted polymers was determined in terms of capacity and selectivity, and the polymer synthesized by using chloroform as solvent resulted in the highest capacity and selectivity.The adsorption mechanism was investigated by using Scatchard analysis. ~1H NMR was used to assess the formation of H-bond between imprinted molecule and monomer in order to provide an insight into the molecular interaction between solvent with template molecule and monomer, respectively. The solvation energy, an intensity index of the molecular interactions between solvent with imprinted molecule and solvent with monomer was calculated with the Density Functional Theory (DFT) method. The MIPs synthesized in the solvent that provided lower solvation energy resulted in better molecular recognition ability, which was in good agreement with experimental observation and ~1H NMR analysis.The results show the importance of solvent choice in molecular imprinting and demonstrate that computational quantum chemistry analysis can assist in choosing a solvent for the synthesis of MIPs.