COMPUTATIONAL MODEL OF ADSORPTION FOR HYDROXYBENZOATE SAXITOXIN DERIVATES (GCs) ON GRAPHENE SURFACE.

Here, we report on the determination of the supramolecular adsorption of hydroxybenzoate derivates (GC toxins) of saxitoxin to pristine graphene surface using the computational method, MMFF94 Force Field implemented in the Chem Office package.

We use a simple model, GC molecule centre in the graphene surface, to simulate the interaction of GC molecule stacking on the graphene system avoiding edges interaction. We find that the formation of the GC–graphene complex is favourable for all GC molecules.

The results of our model are in good agreement with chromatographic elution results on the graphite surface, Hypercarb column. We predict that these aromatic saxitoxin derivatives possess higher adsorption energy than non-aromatic ones. π-π stacking can be regarded as being a prevalent contribution in front of non-aromatic analogues. Furthermore, MMFF94 adsorption results yield qualitative agreement with experiments within N-OH and N-H sub-families:

Computational model, the interaction energy values order is GC6-GC5-GC4-GC3-GC2-GC1 (the highest adsorption energy)

Experimental Hypercarb model, the elution order is GC3-GC6-GC2-GC5-GC4-GC1 (the highest retention time)

The proposed research MMFF94 framework works well in the assessment of chromatographic selectivity. This simple model has potential for use in predicting the qualitative interactions of small polar molecules and graphene which sheds light on the application of computational techniques to help in analytical method development.