Theoretical quantum mechanical based studies of melamine – monomers interaction in pre-polymerisation phase

The need for materials with pre-determined ligand-selectivity in sensing and separation technologies has driven the science of molecularly imprinted polymers (MIPs). MIPs are considered as alternatives to the traditional antibodies used in assays and sensors. They have been increasingly employed in chromatography, sample pre-treatment, purification, catalysts, drug delivery, etc. They show favoured affinity to the template compared to other molecules, and this property is the basic driving force for such applications of these materials. In this work, we have modelled recognition of melamine as a model template by 13 functional monomers using density functional theory (DFT) method at ωB97X-D/6-31G(d) level of theory. Three monomers, namely 2-acrylamido-2-methyl-1-propanesulphonic acid (AMPSA), itaconic and acrylic acid, were identified as the best candidates for creation of MIPs for melamine. In order to predict selectivity of melamine-imprinted polymers, the binding energies of AMPSA, itaconic and acrylic acid were tested with two other molecules: penicillin and atrazine. It was shown that 1:1 AMPSA complex with melamine is more energetically favourable (−39.2 kcal/mol) than with penicillin (−21.2 kcal/mol) as well as with atrazine (−18.7 kcal/mol). Therefore, AMPSA can be recommended as the best functional monomer for creation of the MIPs with highest selectivity to melamine.