Two-Dimensional Self-Assembly of BODIPY Derivatives\nwith Different Functional Groups at the Liquid–Solid Interface

The\n4,4-difluoro-boradiazaindacene (BODIPY) unit possesses a rigid\naromatic backbone, which facilitates the formation of self-assemblies\nand aggregates. However, most current studies on the self-assemblies\nof BODIPY derivatives have relied on spectroscopic methods to indirectly\ngather information about the self-assembled structures. In this study,\nwe presented three BODIPY derivatives (B-3OC<sub>12</sub>, B-3OC<sub>12</sub>-2I, and B-DOB-2OC<sub>12</sub>) that shared the same core\nbut were decorated with different functional groups. The self-assembled\nstructures were revealed using scanning tunneling microscopy (STM)\nin combination with density functional theory (DFT). The results showed\nthat all the molecules self-assembled into lamellar structures. When\nmodified with three dodecyloxy chains or with the introduction of\nadditional halogen atoms, the B-3OC<sub>12</sub> and B-3OC<sub>12</sub>-2I molecules tended to distribute in a staggered form to build a\ntetramer or dimer. In contrast, the B-DOB-2OC<sub>12</sub> molecule,\nwhich contains a dioxaborole group, self-assembled in a head-to-tail\nmanner. These results demonstrated that BODIPY derivatives self-assembled\ninto different structures, depending on their distinct patterns of\nintermolecular interactions influenced by functional groups.