Showing papers by "Peter H. Beton published in 2012"
71 citations
TL;DR: It is shown that the random organization of a two-dimensional supramolecular array of isophthalate tetracarboxylic acids varies with subtle chemical changes in the system, quantifying this variation using an order parameter and revealing a phase behaviour that is consistent with long-standing theoretical studies on random tiling.
Abstract: Assembling random networks on a surface is an intriguing — and potentially useful — phenomenon, but partial order is difficult to control. Researchers have now altered two-dimensional tetracarboxylic acid networks through only small chemical changes. This phase behaviour reveals that entropy, alongside energy, plays a crucial role in the order–disorder balance.
60 citations
TL;DR: In this paper, the authors show that at large tile densities there is a phase transition from a fluid of rhombus tiles to a solid packing with broken rotational symmetry.
Abstract: We study the covering of the plane by nonoverlapping rhombus tiles, a problem well studied only in the limiting case of dimer coverings of regular lattices. We go beyond this limit by allowing tiles to take any position and orientation on the plane, to be of irregular shape, and to possess different types of attractive interactions. Using extensive numerical simulations, we show that at large tile densities there is a phase transition from a fluid of rhombus tiles to a solid packing with broken rotational symmetry. We observe self-assembly of broken-symmetry phases, even at low densities, in the presence of attractive tile-tile interactions. Depending on the tile shape and interactions, the solid phase can be random, possessing critical orientational fluctuations, or crystalline. Our results suggest strategies for controlling tiling order in experiments involving "molecular rhombi."
26 citations
Journal Article•
TL;DR: It is shown that at large tile densities there is a phase transition from a fluid of rhombus tiles to a solid packing with broken rotational symmetry, and strategies for controlling tiling order in experiments involving "molecular rhombi".
Abstract: We study the covering of the plane by nonoverlapping rhombus tiles, a problem well studied only in the limiting case of dimer coverings of regular lattices. We go beyond this limit by allowing tiles to take any position and orientation on the plane, to be of irregular shape, and to possess different types of attractive interactions. Using extensive numerical simulations, we show that at large tile densities there is a phase transition from a fluid of rhombus tiles to a solid packing with broken rotational symmetry. We observe self-assembly of broken-symmetry phases, even at low densities, in the presence of attractive tile-tile interactions. Depending on the tile shape and interactions, the solid phase can be random, possessing critical orientational fluctuations, or crystalline. Our results suggest strategies for controlling tiling order in experiments involving "molecular rhombi."
18 citations
15 Mar 2012
TL;DR: In this article, the authors used hydrogen bonds, dipole-dipole, van der Waals interactions, and metal-ligand coordination to construct two-dimensional arrays on surfaces.
Abstract: Two-dimensional assembly of molecular assemblies on surfaces represents a significant challenge to chemists, materials scientists, and physicists. Supramolecular chemistry offers many advantageous strategies for the development of such arrays through the use of intermolecular interactions to control the process of molecular organization and self-assembly. This article reveals how hydrogen bonds, dipole–dipole, van der Waals interactions, and metal–ligand coordination can be used to assemble two-dimensional arrays on surfaces. Such supramolecular assemblies can be used to trap guest species mimicking host–guest chemistry in the solution phase. By the use of the molecular resolution of scanning-probe microscopies, particularly scanning tunneling microscopy, the precise arrangement of the supramolecular assemblies can be probed and evaluated including the relative orientation with respect to the surface. The influence of the surface on the self-assembly process is discussed and it is shown that far from playing a passive role in the self-assembly process the substrate can strongly influence the supramolecular chemistry observed. Such images provide great insight into the advantages and restrictions of working in two dimensions in comparison to the solution phase or the solid state.
Keywords:
supramolecular assembly;
self-assembly;
hydrogen bonding;
dipole–dipole coupling;
host–guest chemistry;
surface chemistry
6 citations