LAUSR

On-surface molecular self-assembly is one of the key paradigms for understanding intermolecular interactions and molecule–substrate interactions at the atomic scale. Phthalocyanines are planar π-conjugated systems capable of self-assembly and can act as versatile, robust, and tunable templates for surface functionalization. One of the ways to tailor the properties of phthalocyanines is by pendant group substitution. How such a scheme brings about changes in the properties of the phthalocyanines at the nanoscale has not been greatly explored. Here we present an atomic-scale picture of the self-assembly of copper phthalocyanine, CuPc, and compare it with its cyano analogue, CuPc(CN)8,on Au(111) using scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) in ultrahigh vacuum (UHV) at 77 K. STM imaging reveals a tetramer unit cell to be the hallmark of each assembly. The periodicity of herringbone reconstruction of Au(111) is unchanged upon CuPc(CN)8 adsorption, whereas for CuPc adsorpt...