Hierarchically Organized Bimolecular Ladder Network Exhibiting Guided One-Dimensional Diffusion
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Abstract
The assembly and dynamics of a hierarchical, bimolecular network of sexiphenyl dicarbonitrile and <i>N</i>,<i>N</i>′-diphenyl oxalic amide molecules on the Ag(111) surface are studied by scanning tunneling microscopy at controlled temperature. The network formation is governed by a two-step protocol involving hierarchic interactions, including a novel carbonitrile–oxalic amide bonding motif. For temperatures exceeding ∼70 K, more weakly bound sexiphenyl dicarbonitrile molecules carry out one-dimensional diffusion guided by the more stable substructure of the network held together by the carbonitrile–oxalic amide bonding motif. A theoretical investigation at the <i>ab initio</i> level confirms the different binding energies of the two coupling motifs and rationalizes the network formation and the diffusion pathway