Structural Transformation of Tetracarboxylic Acids Self-Assembly Structures Regulated by a Pyridine Derivative

In this work, the self-assembly behaviors of tetracarboxylic acid derivatives (EBTD, BCPTD, and DETD) and their co-assembly behaviors with pyridine derivative PEBP-C8 were investigated by scanning tunneling microscopy (STM) and density functional theory (DFT). EBTD, BCPTD, and EBTD molecules self-assembled into similar regular grid structures by forming O–H···O hydrogen bonds. Especially, with a meta -dicarboxylic group, DETD molecules could aggregate into another kind of dimeric building block, leading to more diversified self-assembly nanostructures. With the introduction of PEBP-C8, all of the O–H···O hydrogen bonds in EBTD and BCPTD systems were broken and O–H···N hydrogen bonds were formed with PEBP-C8. In contrast, for the DETD/PEBP-C8 system, partial O–H···O hydrogen bonds were retained along with the new O–H···N bonds with PEBP-C8. Both EBTD and BCPTD co-assembled with PEBP-C8 to form acid–pyridine–acid–pyridine nanostructures. Nevertheless, DETD not only assembled with PEBP-C8 into an acid–pyridine–acid–pyridine nanostructure but also formed a pyridine–acid–acid–pyridine nanostructure.