Dear Colleagues,

Ever since Dalton suggested that the 6-fold symmetry of ice crystals results from the packing of water molecules into hexagonal lattices, the concept of symmetry has been one of the central unifying themes of chemistry. Symmetry arguments, whether explicitly stated or implicitly assumed, underlie many of our most important chemical concepts and inform our understanding of the relationship between the molecular world and observable macroscopic properties. Indeed, it is impossible to engage in a meaningful discussion of many topics, such as abiogenesis, stereochemistry, color and crystallography, without reference to symmetry. Symmetry considerations underpin every step, from conception to culmination, in the process of creating new molecules. The language of synthesis is rife with symmetry-laden terms: chiral, racemic, isotactic, the Woodward-Hoffmann rules, stereoselective synthesis, enantiomer, epimerization, mirror planes and C2-axes, to name just a few examples. Characterization methods also rely heavily on understanding molecular symmetry: are protons homotopic, enantiotopic or diastereotopic? Is an optical transition allowed or forbidden? Materials properties, such as surface chemistry, ferroelectricity, birefringence and second harmonic generation, likewise depend on molecular and supramolecular symmetry. Symmetry can also manifests itself in the most unexpected places; for example, because low symmetry molecules are commonly more soluble than their higher symmetry analogues, isomers with differing symmetry often are conveniently separated by recrystallization.

Many of the examples listed above are well understood by chemists, while others are much less so. This special issue of the International Journal of Molecular Sciences is dedicated to exploring the major lacunae that remain in our understanding of molecular symmetry. Topics to be addressed may include, but are not limited to, challenges in organic synthesis, the effects of symmetry on self-assembly processes, symmetry breaking in the origins of life and the properties of bulk materials.

Vance Williams, Ph.D.
Guest Editor

Related Journal

Symmetry

• synthesis
• spectroscopy
• materials properties
• optics
• abiogenesis
• stereochemistry