The concept of aromaticity after 200 years of benzene

Aromaticity is one of the most influential and widely used concepts in chemistry. Originally introduced to describe the unusual stability and reactivity of benzene, its scope has expanded dramatically over the past two centuries.

In a new Review published in Nature Reviews Chemistry, F. Matthias Bickelhaupt from the Vrije Universiteit Amsterdam, Gabriel Merino from the CINVESTAT in Mérida, and Miquel Solà from the Institute of Computational Chemistry and Catalysisi at UdG, revisit the concept of aromaticity and examine how it has evolved since the discovery of benzene. The authors discuss the fundamental features underlying aromaticity and review major developments that have broadened the concept far beyond classical planar π-electron systems.

Today, aromaticity is invoked not only for conventional two-dimensional ground-state molecules, but also for transition states, three-dimensional structures, excited states, metal-containing compounds, and systems exhibiting σ-, δ- and even φ-aromaticity. As a consequence, the number of compounds described as aromatic has increased enormously, with recent estimates suggesting that around two-thirds of known compounds display some degree of aromatic character.

The Review focuses particularly on three rapidly developing areas: excited-state aromaticity, three-dimensional aromaticity, and metallaaromaticity. At the same time, the authors emphasize the need for a coherent understanding of the different manifestations of aromaticity, which are often described using diverse and seemingly disconnected concepts and criteria.

The work provides a broad perspective on the past, present and future of one of chemistry’s most enduring concepts, and highlights both the richness of modern aromaticity and the challenges associated with its increasingly broad use.

Reference: F. M. Bickelhaupt, G. Merino and M. Solà, The concept of aromaticity after 200 years of benzene, Nature Reviews Chemistry (2026).

Read the article in Nature Reviews Chemistry

Girona, 30th September 2026
For more info: ges.iqcc@udg.edu