We investigated the binding of single and double methane with cyclic/polycyclic aromatic hydrocarbons (benzene, pyrene, and coronene) and also with graphene using density functional theory (DFT) calculations at M06-2X/6-31G(d) level. Our study was also extended to understand the binding of the naturally occurring aromatic amino acids (AAA) with graphene. Two finite size graphene sheets of small graphene (GS) consists of 62 carbon atoms and large graphene sheet (GL) consists of 186 carbon atoms were considered. All geometry optimizations were performed within the symmetry constraints. The optimized geometries were used for single point calculations to obtain the correction for Basis Set Superposition Error (BSSE). In our computational study, the possibilities of different binding modes of methane with aromatic systems include three C-H…π, two C-H…π, one C-H…π interactions. Our detailed computational study of the binding of methane with model aromatic compounds will provide knowledge required for experimentalists developing materials for methane storage or sensors. The binding energies for two methane molecules with the aromatic hydrocarbons are considerably larger than that of single methane binding with respective aromatic system. At least three of the conformers for each of the AAA were chosen to examine the binding with two different graphene sheets. In this study, we built complexes considering 3-4 orientations for each of the three different conformers of AAA to understand their binding affinity with GS and GL. Our aim here is to reveal what is the preferred orientation of the AAA with graphene (π-π vs. C-H/N-H…π) and how does the size of graphene sheet affect the binding strength.

Computational study of the binding of methane and aromatic amino acids with graphene

253rd National Meeting (2017)

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