Influence of Solvophobic Effects on Self-Assembly of Trimesic Acid at the Liquid−Solid Interface

Despite the multitude of surface supported monolayer structures already reported for trimesic acid (TMA), new self-assembled structures are still discovered, depending on conditions and environment. This exemplifies the versatility of this archetypical supramolecular building block and justifies its role as a model system. At the interface between 1-phenyloctane (PO), a highly nonpolar solvent, and graphite, a new densely packed and partly hydrogen-bonded TMA structure is observed by means of scanning tunneling microscopy (STM). Normally, the TMA solubility in PO is too low to allow for self-assembly of interfacial monolayers. However, as verified by UV−vis spectroscopy, sonication of solutions with TMA sediment increases the amount of dissolved solute molecules. Consequently, the self-assembly of interfacial monolayers can be observed with these enriched solutions. In contrast to many other structures reported, the observed monolayers are densely packed and composed of partly hydrogen-bonded TMA molecule...