Multiple Two-Dimensional Structures Formed at Monolayer and Submonolayer Coverages of p-Sexiphenyl on the Au(111) Surface

Abstract

The two-dimensional structures formed by monolayers and submonolayers of p-sexiphenyl (p-6P) molecules evaporated onto the Au(111) surface are investigated using ultrahigh vacuum scanning tunneling microscopy (UHV-STM). Five different 2D structures corresponding to different surface coverages are discovered and their 2D structures solved. The trends in the molecular alignment with respect to the underlying gold lattice are discussed. An unusual structure that consists of paired rows of p-6P molecules was discovered. A surface structure with alternating domains of slightly differently packed p-6P molecules was also found. The boundary between these two domains contains systematic molecular vacancies.

Statistical Thermodynamics of Lattice Gas Models of Multisite Adsorption

“…Further increasing in the electrode potential leads to the surface phase which is formed only by molecules oriented perpendicular to the surface. Analogous sequence of the ordered structures was also observed in other systems, in particular, in p-sexiphenyl [18] and pyridine adsorption monolayers [23] on Au (111). Thus, the phase behavior of monolayer adsorption which is realized in the model under consideration is qualitatively the same as the phase behavior of real adsorption monolayers of complex organic molecules on homogeneous surfaces.…”

“…Obviously that the adsorption of more complex (in regard geometry, the chemical structure -the presence of double/triple bonds or several functional groups) of molecules is even more nontrivial [14][15][16][17][18][19][20][21][22][23][24][25]. First of all this is manifested in that complex organic molecules (cyclic hydrocarbons, aromatic systems etc.)…”

“…Indeed, over the past ten years series of experimental works devoted to the study of organic selfassembled monolayers on metal surfaces has been published. The general conclusion of these studies is that the molecule orientation in the adlayer is a function of external parameters such as concentration, pressure, temperature, electrode potential and others [14][15][16][17][18][19][20][21][22][23][24][25]. Moreover, very interesting ordered structures have been experimentally found in some of similar systems.…”

“…Those are structures which simultaneously contain the molecules with different orientations in the adlayer. For example, in [18] the authors investigated behavior of the adsorption monolayer of molecules p-Sexiphenil on the Au(111) surface in ultrahigh vacuum using the method of scanning tunneling microscopy. It was shown that five various ordered structures two of which contain molecules with different orientations in the adlayer -molecules oriented parallel to the surface and tilted to the surface at an angle can be formed.…”

Self-Assembly of Nanoporous Chiral Networks with Varying Symmetry from Sexiphenyl-dicarbonitrile on Ag(111)

“…This kind of position has already been found for sexiphenyl molecules on Au(111), where they show the tendency to adopt orientations centering as many phenyl rings as possible over substrate atom centers. 51 In both stripes of the dense-packed phase, molecular adsorption sites repeat every fourth NC-Ph 6 -CN molecule along the stripe direction. Thus, the unit cell contains four molecules in each kind of nanostripe.…”