Chapter 23.6 Halogen interactions in biomolecular crystal structures

Crystallography of biological macromolecules

Second Online Edition (2012)

Part 23. Structural analysis and classification

  1. M. J. Vallejos1,
  2. P. Auffinger2,
  3. P. S. Ho1

Published Online: 14 APR 2012

DOI: 10.1107/97809553602060000895

International Tables for Crystallography

International Tables for Crystallography

How to Cite

Vallejos, M. J., Auffinger, P. and Ho, P. S. 2012. Halogen interactions in biomolecular crystal structures. International Tables for Crystallography. F:23:23.6:821–826.

Author Information

  1. 1

    Department of Biochemistry and Molecular Biology, 1870 Campus Delivery, Colorado State University, Fort Collins, CO 80523–1870, USA

  2. 2

    Institut de Biologie Moléculaire et Cellulaire, Centre National de la Recherche Scientifique, Unité Propre de Recherche 9002, Université de Strasbourg, 15 Rue René Descartes, F‐67084 Strasbourg, France

Publication History

  1. Published Online: 14 APR 2012



Electron‐rich halogens are increasingly seen in biomolecular structures, particularly as they become incorporated into proteins and nucleic acids to facilitate phasing of X‐ray diffraction data, and into ligands to increase their efficacies as inhibitors and drugs. Recently, we have had to reassess our basic understanding of how halogens contribute to the structures and stabilities of biological macromolecules and their complexes, with the recognition of new classes of non‐covalent interactions that are available to the Group IV atoms and a rekindled interest in halogen bonds. We review here the current understanding of the molecular properties of halogens and how these contribute to the variety of non‐covalent interactions seen in halogenated molecules that are important in biology.


  • halogen interactions;
  • aromatic halogen bonds;
  • halogen‐bond acceptors;
  • halogen‐bond geometries