Solvent Coadsorption Effect on I···O Halogen-Bonded 2D Self-Assembled Nanostructures

A halogen bond, as an important driving force, has tremendous application and potential in drug design, crystal engineering, organic photoelectric material, and catalysis. However, reports on the I···O heterogeneous halogen bond-induced 2D self-assembly are rare. Herein, we explore the effect of solvent coadsorption on the I···O heterogeneous halogen-bonded 2D self-assembled nanostructures of 4-(5-iodothiophen-2-yl)­phenyl 3,4,5-tris­(octadecyloxy)­benzoate (I-TPB) at the aliphatic solvent/graphite interfaces by scanning tunneling microscopy and density functional theory calculation. n-Tridecane, n-tetradecane, and n-pentadecane are chosen as the solvents. I-TPB molecules form the same linear pattern in all the solvents at high solution concentrations. The dot-like nanostructure in n-tetradecane and n-pentadecane at low concentrations is observed. The solvent coadsorption in the dot-like nanostructure of the I-TPB adlayer does not change the intermolecular I···O halogen bonds, I···H hydrogen bonds, and S···H interactions in each dimer. The results illustrate that the intermolecular I···O halogen bonds, I···H bonds, and S···H interactions in those dimers are the main driving forces to stabilize the self-assembled nanostructures, whereas the dipole–dipole interactions are the complementary forces. This work presents significant insights into the formation mechanism of self-assembled nanostructures associated with the I···O heterohalogen bond in order to construct ideal self-assembled structures.