Two-dimensional molecular sieves: structure design by computer simulations

Abstract

Nanoporous molecular networks formed spontaneously by organic molecules adsorbed on solid substrates are promising materials for future nanotechnological applications related to separation and catalysis. With their unique ordered structure comprising nanocavities of a regular shape planar networks can be treated as 2D analogs of bulk nanoporous materials. In this report we demonstrate how the Monte Carlo simulation method can be effectively used to predict morphology of self-assembled porous molecular architectures based on structural properties of a building block. The simulated results refer to the assemblies created by cross-shaped organic molecules which are stabilized by different intermolecular interactions, including hydrogen bonding and van der Waals interactions. It is demonstrated that tuning of size and aspect ratio of the building block enables the creation of largely diversified extended structures comprising pores of a square and rectangular shape. Our theoretical predictions can be helpful in custom design of functional adsorbed overlayers for controlled deposition, sensing and separation of guest molecules.

Tailoring Large Pores of Porphyrin Networks on Ag(111) by Metal–Organic Coordination

“…The experimental results reveal striking differences in the formation of metal–organic coordination networks and the corresponding coordination motifs, despite the similarities of the systems, that is, mononuclear Cu nodes coordinated to nitrogen of quasi‐fourfold symmetric porphyrins on Ag(111). To rationalize the experimental findings, Monte Carlo modeling was performed, as structure formation is known to be correctly reproduced in such simple simulations for a variety of functional tectons, including porphyrins and phthalocyanines . For these simulations, both TPyPP and TPCN are represented by a fourfold symmetric cross and metal adatoms are depicted as circles (e.g., inset in Figure a), following a representation previously introduced for similar systems .…”

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

“…Selected segments were activated to represent different intramolecular distribution of the active centers. The interactions between the activated segments were described by a short range segmentsegment interaction potential limited to nearest neighbors on a square lattice and characterized by = -1 expressed in kT units [25,26]. Fig.…”

“…Among computational methods, Monte Carlo lattice approach seems to be the most effective, allowing for investigation of system with large number of molecules under variable conditions, where the geometry of building blocks as well as interactions can be described with relatively low number of adjustable parameters [17][18][19][20][21][22][23][24][25][26]. This simple coarse-grained MC model was recently used by us to explore the effect of aspect ratio and relative position of molecular arms in cross-shaped molecules [25] and the role of the number and position of the interaction centers on the morphology of the corresponding 2D assemblies. In this contribution we use the adopted approach to investigate the effect of intramolecular distribution of active centers in an asymmetric building block on the superstructures formation in adsorbed overlayers.…”

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

“…bulky substituent), less directional forces like van der Waals can trigger a self-assembly of adsorption layers. 11,16,17 On the other hand, we should not neglect the role of the surface in the self-assembly of organic adsorption layers. It is usually believed that weak non-covalent interactions between a molecule and a relatively inert surface (such as van der Waals or dispersion forces) determine only the conformation of the adsorbed molecules, whereas intermolecular interactions only affect the structure of the self-assembling adsorption layer.…”

“…The adsorption of organic molecules with different amounts of functional groups and the symmetry of their arrangement were investigated. 17,[42][43][44][45][46][47][48][49][50][51][52] Phase transitions, their order and universality class have been analyzed for the simplest models. [53][54][55][56][57] In this work, using a simple lattice gas model we study the features of the self-assembly in adsorption layers where both ''adsorbate-adsorbate'' and ''adsorbate-adsorbent'' interactions are anisotropic.…”