Standard Article

Supramolecular Isomerism

Supramolecular Materials Chemistry

  1. Susan A. Bourne

Published Online: 15 MAR 2012

DOI: 10.1002/9780470661345.smc124

Supramolecular Chemistry: From Molecules to Nanomaterials

Supramolecular Chemistry: From Molecules to Nanomaterials

How to Cite

Bourne, S. A. 2012. Supramolecular Isomerism. Supramolecular Chemistry: From Molecules to Nanomaterials. .

Author Information

  1. University of Cape Town, Cape Town, South Africa

Publication History

  1. Published Online: 15 MAR 2012

Abstract

Supramolecular isomers comprise network structures that have identical chemical compositions but differ from one another in their structure. In some instances, the term is also used to describe identical frameworks that contain different counterions, solvent, or guest molecules. Supramolecular isomerism can be observed in both molecular and coordination compounds. Like polymorphism, it results when different, but energetically similar, packing interactions can operate during crystallization.

Gaining control on crystallization of a particular isomer remains challenging as both thermodynamic and kinetic factors play a role, and as understanding the full energy profile of a self-assembly process is extremely difficult. Some important variables within the crystallization system have been identified, including chemical and physical factors, which are described in this chapter.

Supramolecular isomers may be considered in four categories: structural, conformational, interpenetrated, and chiral networks. Examples of each are provided. A number of topological approaches have been described over the years, which aid in the description of extended structures. Both graph set and network analyses are useful for this purpose.

Crystal engineering aims to control structural characteristics of crystalline materials, with the aim of having greater control over their physical properties. Although hydrogen-bonded supramolecular synthons have been studied in depth for more than a decade and although coordination bonds are stronger and more directional than other supramolecular interactions, structural uncertainty is still a characteristic of self-assembled systems. Some structure-property relationships are emerging, including luminescence and porosity.

Keywords:

  • supramolecular isomer;
  • crystal engineering;
  • network;
  • polymorph;
  • packing interactions