The halogen bond: an interim perspective

Area of Science:

• Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• The halogen bond is a significant non-covalent interaction gaining research interest.
• It shares similarities with the more familiar hydrogen bond.
• Understanding its fundamental nature is crucial for novel applications.

Purpose of the Study:

• To elucidate the fundamental nature of the halogen bond in the gas phase.
• To review recent advancements and applications of halogen bonding in diverse chemical and material contexts.
• To provide an interim definition for the halogen bond based on structural similarities to hydrogen bonds.

Main Methods:

• Systematic investigations of rotational spectra of Lewis base-dihalogen complexes (B...XY).
• Comparative analysis of geometric structures between halogen-bonded (B...XY) and hydrogen-bonded (B...HX) systems.
• Review of literature on recent applications in crystal engineering, liquid crystals, nanomaterials, polymer chemistry, and inorganic chemistry.

Main Results:

• The geometry of B...XY complexes is isomorphic to B...HX hydrogen-bonded systems.
• This structural similarity supports a new, interim definition of the halogen bond.
• Novel applications highlight the utility of halogen bonds, particularly with XR molecules (R=electron-withdrawing group), in various scientific fields.

Conclusions:

• The halogen bond is a well-defined interaction with predictable geometric outcomes.
• Its fundamental understanding facilitates its application in advanced materials and chemical synthesis.
• The continued exploration of halogen bonding promises further innovation across scientific disciplines.