<p>Nanofabrication of tunable two-dimensional (2D) supramolecular architecture relies on the delicate balance between molecule-molecule and molecule-substrate interactions, where carefully designed molecules as building blocks are required. In this study, we introduced isopropylethynyl groups into two tripodal molecules, <i>i.e.</i>, 1,3,5-tris-(isopropylethynyl)-benzene (<i>i</i>Pr-TEB) and 2,4,6-tris-(isopropylethynyl)-1,3,5-triazine (<i>i</i>Pr-TET), and investigated their self-assembly on Au(111) and Ag(111) surfaces under ultra-high-vacuum using scanning tunneling microscopy (STM). On Au(111) and Ag(111), <i>i</i>Pr-TEB formed relatively comparable self-assembled nanopatterns through side-by-side dimers aggregation. These subtle differences in aggregation correlate with their negligible variations in adsorption conformation and energy. In contrast, <i>i</i>Pr-TET exhibited pronounced substrate-dependent adsorption geometries due to stronger molecule-substrate interactions, resulting in disparate self-assembled nanoarchitectures on these two surfaces. Our results highlight the rotational flexibility of the isopropyl groups enabled by the single bond connecting them to the main acetylenic core, modulating intermolecular interactions and fine-tuning molecule-substrate interactions strength, hence providing a new strategy for crystal engineering in two dimensions.</p>

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Substrate-mediated Self-assembly of 1,3,5-Benzene/Triazine Functionalized by Flexible Isopropylethynyl Groups

  • Yu Lin,
  • Sifan You,
  • Miao Xie,
  • Meng Zhang,
  • Chaojie Xu,
  • Lifeng Chi

摘要

Nanofabrication of tunable two-dimensional (2D) supramolecular architecture relies on the delicate balance between molecule-molecule and molecule-substrate interactions, where carefully designed molecules as building blocks are required. In this study, we introduced isopropylethynyl groups into two tripodal molecules, i.e., 1,3,5-tris-(isopropylethynyl)-benzene (iPr-TEB) and 2,4,6-tris-(isopropylethynyl)-1,3,5-triazine (iPr-TET), and investigated their self-assembly on Au(111) and Ag(111) surfaces under ultra-high-vacuum using scanning tunneling microscopy (STM). On Au(111) and Ag(111), iPr-TEB formed relatively comparable self-assembled nanopatterns through side-by-side dimers aggregation. These subtle differences in aggregation correlate with their negligible variations in adsorption conformation and energy. In contrast, iPr-TET exhibited pronounced substrate-dependent adsorption geometries due to stronger molecule-substrate interactions, resulting in disparate self-assembled nanoarchitectures on these two surfaces. Our results highlight the rotational flexibility of the isopropyl groups enabled by the single bond connecting them to the main acetylenic core, modulating intermolecular interactions and fine-tuning molecule-substrate interactions strength, hence providing a new strategy for crystal engineering in two dimensions.