Cross-impact of surface and interaction anisotropy in the self-assembly of organic adsorption monolayers: a Monte Carlo and transfer-matrix study

Abstract

abUsing a simple lattice gas model we study the features of self-assembly in adsorption layers where both ''molecule-surface'' and ''molecule-molecule'' interactions are anisotropic. Based on the example of adsorption layers of mono-functional organic molecules on the heterogeneous surface with strip-like topography, we have revealed plenty of possible self-assembled structures in this simple system, such as discrete, linear, zigzag, chess board-like, two-dimensional porous and close-packed patterns. However, the phase behavior of the adsorption layer is much richer, if the interactions between functional and non-functional parts of adjacent adsorbed molecules have comparable strength and opposite signs. It is demonstrated that filling of the strips composed of relatively ''strong'' adsorption sites with the increase of chemical potential can be non-monotonic. This effect is associated with surface anisotropy and results from the changing of the driving force of the self-assembly process -interactions between the adsorbed molecule and the surface dominate at low surface coverages, but intermolecular forces prevail at higher ones. Additionally, when the width of the strip composed of ''strong'' adsorption sites is two or more times greater than that of the adsorbed molecule, a local assembly of the ordered phases on the ''strong'' adsorption sites is observed. Our results suggest strategies for controlling the self-assembly in experiments involving mono-functional organic molecules on a strip-like heterogeneous surface.

Halogenated Anthracenes as Building Blocks for the On-Surface Synthesis of Covalent Polymers: Structure Prediction with the Lattice Monte Carlo Method

“…In those instances, it has been possible to establish the structure–property relationship between a molecular building block and the resulting assembly and to identify basic molecular features responsible for the formation of a given superstructure. In this field, methods such as molecular dynamics − and Monte Carlo simulations − have been used most frequently. The latter method, especially in its coarse-grained variant, revealed to be a powerful tool that allowed for the fast and correct prediction of adsorbed superstructures, including molecular networks, , strings, cyclic oligomers, , fractal aggregates, , and others. , The MC method has also been used to study metal–organic systems on surfaces, demonstrating the possibility of steering the self-assembly by manipulating intrinsic properties of contributing molecules. ,− …”

Chemical Potential and Thermodynamic Properties of Self-Assembled Monolayers: A Method of External Fields in a Monte Carlo Simulation

“…Further refining of the tripod model was done by incorporation of patchy interaction centers . It should also be mentioned that there are a few papers devoted to self-assembly of cross-shaped molecular blocks, − which could model porphyrin or phtalocyanine molecules.…”

Modeling of the 2D self-assembly of tripod-shaped functional molecules with patchy interaction centers

“…The coarsegrained picture mentioned above has been frequently used in the Monte Carlo (MC) simulations of adsorbed systems on solid substrates. This refers to simple rod-like molecules (Matoz-Fernandez et al 2008;Centres and Ramirez-Pastor 2009;Nieckarz and Szabelski 2013) as well as to molecules with more complex structures, including cross-shaped units resembling porphyrins and phthalocyanines (Li and Lin 2011;Akimenko et al 2015;Kasperski et al 2015;Bischoff et al 2016;Gorbunov et al 2017), tripod-shaped tectons corresponding to tricarboxylic acid derivatives (Ibenskas and Tornau 2012;Misiunas and Tornau 2012;Šimenas et al 2015), dehydrobenzoannulenes (DBAs) (Szabelski et al 2010;Adisoejoso et al 2012) and molecules bearing pyridyl (Ciesielski et al 2013) and nitrile (Copie et al 2015) groups. The results from these theoretical studies demonstrate that the MC calculations, performed even for the simplified molecular representations, are able to reproduce correctly formation and coexistence of various adsorbed phases observed experimentally, especially the planar nanoporous networks observed either in ultra high vacuum or at the liquid/solid interface.…”