Concentration-Dependent Supramolecular Engineering of Hydrogen-Bonded Nanostructures at Surfaces: Predicting Self-Assembly in 2D

Abstract

We report a joint computational and experimental study on the concentration-dependent self-assembly of a flat C3-symmetric molecule at surfaces. As a model system we have chosen a rigid molecular module, 1,3,5-tris(pyridine-4-ylethynyl)benzene, which can undergo self-association via hydrogen bonding (H-bonding) to form ordered 2D nanostructures. In particular, the lattice Monte Carlo method, combined with density functional calculations, was employed to explore the spontaneous supramolecular organization of this tripod-shaped molecule under surface confinement. We analyzed the stability of different weak H-bonded patterns and the influence of the concentration of the starting molecule on the 2D supramolecular packing. We found that ordered, densely packed monolayers and 2D porous networks are obtained at high and low concentrations, respectively. A concentration-dependent scanning tunneling microscopy investigation of the molecular self-assembly at a graphite-solution interface revealed supramolecular motifs, which are in perfect agreement with those obtained by simulations. Therefore, our computational approach represents a step forward toward the deterministic prediction of molecular self-assembly at surfaces and interfaces.

Directing the Self-Assembly of Tripod Molecules on Solid Surfaces: A Monte Carlo Simulation Approach

“…7,10,15 In the adopted approach the basic molecular building block consisted of four interconnected segments arranged in a tripod with a core and three arms of equal length (one segment each). One molecular segment was allowed to occupy one adsorption site on a triangular lattice representing a (111) crystalline surface.…”

“…7,10,15,[22][23][24][25][26] This approach allows for selective observation of the 2D structures formed by just one type of molecular conformer without interference of the remaining ones. Such information can be especially important when a molecule with fixed position of interaction centers (no ratability is allowed) is to be synthesized to create an adsorbed superstructure with predefined morphology.…”

Effects of Alkyl Chain Length and Hydrogen Bonds on the Cooperative Self‐Assembly of 2‐Thienyl‐Type Diarylethenes at a Liquid/Highly Oriented Pyrolytic Graphite (HOPG) Interface

“…[39,40] Polymorphs on 2D surfaces that arise from ad ifference in the concentration of the solution phase has attracted considerable attention,s ince it provides important insights into thermodynamic properties of surface-confined self-assemblies. [41][42][43][44][45] De Feyter et al have rationally interpreted an origin of polymorphs by considering the surface density of two different phases and the adsorption energiesp er molecule. [46] Althought he concentration dependence of such phaset ransitions between two or more different orderings hasb een well documented, much less is known about the mechanism that underlies ordering formation that occurs on an unoccupied surfacewithincreasing concentrationo fs olute.…”

Thermodynamic versus kinetic control in self-assembly of zero-, one-, quasi-two-, and two-dimensional metal-organic coordination structures

“…Interestingly, the four bi-component systems behaved differently upon thermal annealing treatments. Using Monte Carlo (MC) simulation, [21][22][23][24] we investigated how the dimensionality of the supramolecular structures affects their thermodynamic properties. In particular, the simulations revealed that the structures with different dimensionalities exhibited distinctive specific heat characteristics, [25][26][27] consistent with the experimental observations.…”