Two-Dimensional Structures Composed of Cross-Shaped Molecules Adsorbed on Solid Surfaces – a Computational Model

Abstract

The ability of simple molecular building blocks to form extended ordered patterns by adsorption and self-assembly on solid substrates is an advantageous property that has been widely used to create nanostructured surfaces. In this contribution we demonstrate how the lattice Monte Carlo simulation method can be used to predict morphology of adsorbed overlayers comprising simple functional cross-shaped molecules resembling phthalocyanines and porphyrins. In particular, we focus on the influence of the distribution of active interaction centers within a model crossshaped molecule on the structure of the resulting molecular networks. Additionally, we investigate how using racemic mixtures of input prochiral molecules affects the chirality and porosity of the corresponding ordered patters. The obtained results show that suitable manipulation of the chemistry of cross-shaped building block allows for the controlled creation of largely diversified molecular porous networks.

Theoretical Modeling of Surface Confined Chiral Nanoporous Networks: Cruciform Molecules as Versatile Building Blocks

“…These calculations were carried out for enantiopure (R) and racemic (R + S) overlayers comprising N cross‐shaped molecules in total. We used the MC simulation method in the Canonical Ensemble combined with the orientationally biased sampling . The simulation algorithm was organized as follows.…”

“…An interesting perspective coming from the theoretical investigations of the achiral and prochiral cruciforms is the possibility of directing their self‐assembly by a suitable manipulation of molecular size, shape, and intramolecular distribution of discrete interaction centers. As the previous studies concentrated mainly on the enantiopure overlayers and the racemic mixtures of small building blocks, in this study we extend our studies and focus on larger structural units that offer more flexibility in adjusting the number and distribution of the active centers. To that purpose we used the lattice MC modeling and identified the main structural differences between enantiopure and racemic assemblies formed by prochiral cross‐shaped molecules bearing a few differently distributed interaction centers.…”

“…In previous studies we have demonstrated that the simple MC model based on a coarse‐grained representation of star‐shaped molecules such as tripods and cruciforms is able to reproduce correctly the self‐assembly of these tectons on solid substrates. Those results showed clearly that the star‐shaped building blocks, even when intrinsically achiral, are able to create globally chiral adsorbed structures that comprise regularly spaced nanopores.…”

“…In this case, detailed information on how these molecular properties affect morphology of the corresponding assemblies can substantially reduce efforts associated with synthesis of the optimal structural unit. Theoretical methods have been an effective predictive tool for the controlled self‐assembly of various molecular tectons …”

“…Theoretical methods have been an effective predictive tool for the controlled selfassembly of various molecular tectons. [16][17][18][19][20][21][22][23][24][25][26][27][28] Recent applications of theoretical methods in the field of 2D molecular self-assembly have brought complementary input on the influence of molecular parameters 16,17 and external conditions 17-20 on the structure formation in adsorbed overlayers comprising star-shaped molecules. Among them such techniques as molecular dynamics [21][22][23] and Monte Carlo (MC) 5,29,[16][17][18][19][20][21]24 simulations have been most frequently used to explore spontaneous organization of large molecular assemblies into extended superstructures.…”