Specific Intermolecular Interactions in the Supramolecular Structure of 5-Hydroxy-6-Methyluracil: A DFT Study of the Hydrogen-bonded Dimers

Studying the self-assembly of uracil derivatives has great importance for biochemistry and nanotechnology. For example, modification of the sorbent surfaces by 5-hydroxy-6-methyluracil (HMU) enhances their adsorption activity. It is assumed that these changes are caused by the self-assembly of the network-like supramolecular associates of the uracil derivative on the sorbent surface. In the present work, the relative stabilities of 15 hydrogen-bonded dimers HMU have been studied by the TPSSh/TZVP density functional theory method and the strengths of the noncovalent interactions analyzed in terms of the reduced density gradient and natural bond orbital approaches. It was found that the symmetric dimer stabilized by two intermolecular hydrogen bonds N1-H...O-C2 (dimer 1-1) is the most stable. This suggests that the self-assembly of HMU should occur through the intermediate formation of the dimer 1-1. The results may be useful for understanding the processes of self-assembly of the uracil derivatives and the rationalized design of the uracil-based supramolecular structures with specific properties.