Halogen-Bond-Based Molecular Self-Assembly on Graphene Surface: A First-Principles Study

The formation of halogen-bond-based 2D supramolecular assemblies on solid surfaces has become a hot research topic in recent years. Herein, we report a theoretical study of the halogen-bonded network formation of pyridine derivatives and aryl–halide molecules on graphene surface using first-principles density functional theory (DFT) calculations. To unravel the characteristics of molecule–molecule and molecule–substrate interactions, the noncovalent interaction index (NCI), electron density difference (EDD), density of state (DOS), and topographical scan tunneling microscopy (STM) image analyses were undertaken. The N···I interactions between terminal pyridyl groups and iodoperfluorobenzenes are predicted to be somewhat stronger than the molecule–surface stacking interactions and appear to be the primary interactions in the self-assembled networks, with geometries in good agreement with the experimental STM images. The results reported in this work should be of great importance in the applications of these interactions in molecular self-assembly on surfaces.