Halogen Bonding in Supramolecular Chemistry

Halogen bonding is a highly directional noncovalent interaction in which an electrophilic region on a halogen atom engages with a nucleophilic site in a partner molecule. This interaction arises from anisotropic electron distribution around the halogen, often termed a sigma-hole, and has emerged as a versatile tool for the design of organised molecular assemblies. In supramolecular chemistry, halogen bonds complement traditional hydrogen bonds and metal coordination, offering precise control over geometry, strength and selectivity. Their tunable interaction energies—ranging typically from 5 to 40 kJ mol⁻¹—allow the construction of crystalline frameworks, responsive materials and recognitive hosts that operate under mild conditions. Applications span from the modulation of solid-state packing and crystal engineering to the development of selective anion receptors, liquid-phase sensors and catalysts.

Global interest in halogen bonding continues to grow, driven by unique attributes such as high directionality, hydrophobic compatibility and the ability to engage in three-centre interactions with halonium ions. Recent advances have demonstrated the integration of halogen bonds into functional devices, including membrane transporters, molecular machines and drug-target complexes. These developments underscore the broad potential of halogen bonding to impact fields as diverse as materials science, chemical biology and environmental sensing.

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Halogen Bonding in Supramolecular Chemistry publication trend

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Technical terms

Halogen bond: A noncovalent attraction between an electrophilic region on a halogen atom and a nucleophilic site on another molecule, characterised by high directionality.

Sigma-hole: An area of positive electrostatic potential on a halogen atom located opposite a covalent bond, enabling interaction with electron donors.

Halonium ion: A positively charged species (e.g., [R–X–R]⁺) that bears an empty p-orbital, capable of forming strong three-centre halogen bonds with Lewis bases.

Lewis base: A molecule or ion that donates an electron pair to form a noncovalent interaction or coordinate bond with an electrophilic centre.

References

1. Sigma-Hole Interactions in Anion Recognition. Chem (2018).
2. Looking Back, Looking Forward at Halogen Bonding in Drug Discovery. Molecules (2017).
3. Halogen bonds of halonium ions. Chemical Society Reviews (2020).