Synthesis and Scanning Tunneling Microscopy Observation of 1,3,5-Triazine Bearing Azo-Carboxylate.

A new compound (2,4,6-tris-(3,5-di-methyl formate-4′-hydroxy azobenzene)-1,3,5-triazine,TDHAT) has been synthesized and the scanning tunneling microscopy (STM) is utilized to clarify the geometrical configuration on the highly oriented pyrolytic graphite (HOPG) surface. The star-shaped molecule self-assembles into uniform and regular triangular petal structure at liquid–solid interface, and high-resolution images has been obtained, which implied a high stability of this two dimensional configuration. The distance between the scattered bright spot and the center of the petal is measured to be about 1.2 nm (L₂), which corresponds to the actual size of each arm. Moreover, a comparison has been made between the TDHAT molecule and the TMA 4a molecule which has similar star-shaped structure with a long alkyl chain at the each end of the three arms, drawing a conclusion that both the structure of arms and the substituent groups would impact the nanoarchitecture. The results give us insight into a better comprehension of the self-assembly of the star-shaped molecule, which benefits the construction of functional nanostructures.