Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rh

Abstract

The tiling of surfaces has long attracted the attention of scientists, not only because it is intriguing intrinsically, but also as a way to control the properties of surfaces. However, although random tiling networks are studied increasingly, their degree of randomness (or partial order) has remained notoriously difficult to control, in common with other supramolecular systems. Here we show that the random organization of a two-dimensional supramolecular array of isophthalate tetracarboxylic acids varies with subtle chemical changes in the system. We quantify this variation using an order parameter and reveal a phase behaviour that is consistent with long-standing theoretical studies on random tiling. The balance between order and randomness is driven by small differences in intermolecular interaction energies, which can be related by numerical simulations to the experimentally measured order parameter. Significant variations occur with very small energy differences, which highlights the delicate balance between entropic and energetic effects in complex self-assembly processes. 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.

Cite this article

Stannard, A., Russell, J., Blunt, M. et al. Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rhombus tilings. Nature Chem 4, 112–117 (2012). https://doi.org/10.1038/nchem.1199

View full text

>> Full Text:   Broken symmetry and the variation of critical properties in the phase behaviour of supramolecular rh