Shape-persistent macrocycles self-assemble into unique patterns at the liquid/solid interface. STM observations have shown the existence of an ordered honeycomb lattice of tricarbazolo triazolophane macrocycles (tricarbs) at the 1,2,4-trichlorobenzene (TCB)/graphite interface. In this study, three tricarb species initially in honeycomb structure on a highly ordered pyrolytic graphite (HOPG) were simulated via atom-resolved molecular dynamics. This is enabled by an in-house <i>ab initio </i>generated Charmm-compatible force field. Simulation results show that the tricarb with shortest alkyl chain rearranged into a non-ordered structure, while the tricarbs with longer alkyl chains preserve the honeycomb structure. Detailed molecular analysis at nanosecond timescale indicates the rearrangement was induced by TCB molecules, and the long alkyl chain protects the overall honeycomb structure; this is realized by reducing the number of TCB molecules accessible to the honeycomb porous cores and blocking the 2D diffusion of TCB molecules on the HOPG. Our work highlighted the potential of all-atom molecular dynamics simulations in predicting the stability of a designed structure, as well as elucidating the mechanism of disassembling.

Role of alkyl chain length in maintaining the honeycomb structure of tricarbazolo triazolophane macrocycles on the graphite surface understood via atom-resolved molecular dynamics

2019 Spring National Meeting

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