Research Highlights

• Subject Category:
  • Chemistry

Published online: 5 November 2008 | doi:10.1038/nchina.2008.258

Halogen bonding: Pulling together

Felix Cheung

Original article citation

Li, Q. et al. Cooperativity between the halogen bond and the hydrogen bond in H₃NXYHF complexes (X, Y = F, Cl, Br). ChemPhysChem 9, 2265–2269 (2008).

Introduction

© (2008) Wiley Interscience

Intermolecular interactions affect many properties of a substance. For example, hydrogen bonding — one of the strongest forms of intermolecular interaction — is the reason behind the high boiling point of water and the double helical structure of DNA. Qingzhong Li, Jianbo Cheng and co-workers at Yantai University¹ have performed a theoretical study on a weaker and much less well known form of intermolecular interaction, known as halogen bonding. They found that a halogen and a hydrogen bond can cooperate, or work together, to enhance each other's strength.

Halogen bonding is the non-covalent interaction between a halogen atom in one molecule, such as one of the bromine atoms in Br₂, and a negative atom in another molecule, such as the nitrogen in NH₃. The researchers studied the interaction of a halogen bond on a hydrogen bond in three-body systems, each comprising an NH₃, a dihalogen and an HF molecule (such as the one pictured).

Their calculations showed that all systems exhibit positive cooperativity — the binding strengths of the halogen and hydrogen bond are enhanced by each other's presence. The enhancement of the hydrogen bond due to the halogen bond is more pronounced than that of the halogen bond due to the hydrogen bond. Although the influence of the hydrogen bond on the halogen bond is smaller, it is still larger than the influence between two hydrogen bonds, such as those in a three-body system comprising H₃C and two HCN molecules.

The findings help paint a clearer picture of the cooperative and competitive role of halogen and hydrogen bonds, which is essential for understanding molecular recognition, crystal engineering and biological systems.

The authors of this work are from:
Laboratory of Theoretical and Computational Chemistry, Science and Engineering College of Chemistry and Biology, Yantai University, Yantai, China.

Reference

1. Li, Q. et al. Cooperativity between the halogen bond and the hydrogen bond in H₃NXYHF complexes (X, Y = F, Cl, Br). ChemPhysChem 9, 2265–2269 (2008).  | Article | PubMed |