The self-assembly of a pair of low-symmetry tetracarboxylic acid molecules and their co-assembly with bridging molecules at the liquid–solid interface

Abstract

The supramolecular self-assembly behavior of a pair of low-symmetry tetracarboxylic acid molecules (H₄OBDB and H₄ADDI) and their co-assembly behavior with TMA as a bridging molecule were studied at the liquid–solid interface. Scanning tunneling microscope (STM) observations revealed that H₄OBDB and H₄ADDI molecules both tend to form O-shaped dimers but end up forming different types of self-assembly structures. We also investigated the construction of two-component co-assembly structures by mixing H₄OBDB or H₄ADDI molecules with bridging molecules such as TMA. The two formed co-assembly structures are similar. Based on the analysis of the STM results and the density functional theory (DFT) calculations, the formation mechanism of the assembled structures was revealed.