Supramolecular Self-Assembly of Hexaphenylbenzene Derivatives with Different Symmetry and Number of Carboxylic Acid at Liquid/Solid Interfaces

Abstract

Functional molecules, especially with carboxyl groups are crucial in building supramolecular structures. It is great important to study the effect of the symmetry, number of carboxyl groups on the self-assembly behavior of corresponding molecules. A series of hexaphenylbenzene (HPB) derivatives (HPB-1,3,5-3A, HPB-1,2,4-3A, and HPB-1,4-2A) substituted with different number of carboxyl groups at different position have been synthesized and their self-assembled structures were investigated at both 1-phenyloctane/HOPG and heptanoic acid/HOPG interfaces by using scanning tunneling microscopy (STM) technique. The self-assembled mechanisms of these HPB-based compounds were further studied with the help of density functional theory (DFT) calculations. The results indicate that symmetry and number of carboxyl groups as well as solvent play a significant role on the tuning self-assemble process resulting in various structures.