Noncovalent Interactions in Aromatic Complexes

Noncovalent interactions among aromatic systems underpin a vast array of phenomena in chemistry, biology and materials science. At their core lies π–π stacking, in which aromatic rings engage in face-to-face or T-shaped arrangements, driven by a delicate balance of London dispersion forces, electrostatic quadrupolar interactions and Pauli repulsion. Complementary modes such as CH–π contacts, cation–π and anion–π interactions further enrich the binding landscape, enabling precise molecular recognition in proteins, nucleic acids and supramolecular assemblies. Such interactions govern protein folding pathways, stabilise biomolecular condensates and dictate the assembly of organic semiconductors, porous frameworks and liquid crystals. Recent advances have revealed submolecular features—π-holes in halogenated aromatics or charge-penetration effects—that refine our understanding of how local electron density shapes affinity and selectivity. In drug discovery, tuning heteroaromatic stacking through heteroatom placement, tautomeric state or progressive fluorination has emerged as a strategy to optimise binding energy and kinetics. In materials design, control of offset stacking geometries yields conductive pathways and photoactive domains with tailored charge‐transport properties. Across disciplines, the interplay of theory and experiment—from high‐resolution force microscopy and electron density mapping to quantum mechanical energy decomposition and machine-learning potentials—continues to reveal the energetic origins of aromatic association and unlocks new routes to functional nanostructures, catalysts and therapeutic agents.

Research from Nature Portfolio

Recent studies have employed Kelvin probe force microscopy to directly visualise π-holes on individual halogen-substituted polyaromatic hydrocarbons. These experiments, supported by high-level theoretical calculations, confirm the presence of electron-deficient cavities above the molecular plane and demonstrate their crucial role in adsorption processes on solid surfaces. By correlating submolecular charge distributions with noncovalent binding strengths, this work provides a new window into the modulation of aromatic interactions at the single-molecule level.

Noncovalent Interactions in Aromatic Complexes publication trend

The graph below shows the total number of articles in noncovalent interactions in aromatic complexes across all publications each year (not limited to Nature Index journals).

Technical terms

π-hole: An electron-deficient region above or below an aromatic ring that can attract nucleophiles or contribute to directional binding.

π–π stacking: Noncovalent association of aromatic rings in parallel or edge-on geometries, driven by dispersion and electrostatic interactions.

CH–π interaction: A stabilising contact between a C–H bond and the π electron cloud of an aromatic system.

London dispersion: Attractive forces arising from instantaneous fluctuations in electron density, particularly important in nonpolar systems.

Quadrupolar electrostatics: Electrostatic interactions due to an anisotropic charge distribution in aromatic rings, often modelled as quadrupole moments.

References

1. Visualization of π-hole in molecules by means of Kelvin probe force microscopy. Nature Communications (2023).
2. The Energetic Origins of Pi–Pi Contacts in Proteins. Journal of the American Chemical Society (2023).
3. Systematic Study of Heteroarene Stacking Using a Congeneric Set of Molecular Glues for Procaspase‑6. Journal of Medicinal Chemistry (2023).
4. Protein–Ligand CH−π Interactions: Structural Informatics, Energy Function Development, and Docking Implementation. Journal of Chemical Theory and Computation (2023).