====== Aromaticity ======

{{tag>Undefined}}

The concept of 'Aromaticity' dates back to 1855, when chemist August Hofmann used the word to describe a set of benzene-like compounds that feature phenyl groups. As the name suggests, one common characteristic is that they often have distinctive [[content:life_sciences:human_body:odorousness|odours]].

Over time, it was realised - through x-ray diffraction tests - that the structure of benzene took the form of a ring of six atoms (see [[content:chemistry:benzene]]).  Later, atomic theory gave (partial) detail to the possibilities of the electron-sharing which held the ring together.

In the last few decades however, theorists have realised that the 'aromaticity' concept is far more complicated than was initially thought.

To the extent that it could now be said that discussions about the entire field are currently in crisis - some experts have even called the concept 'non-existent' [source below].

>Numerous computational tools for aromaticity analysis have been introduced and novel classes of molecules that exhibit aromatic (or antiaromatic) features have been explored experimentally. __Hence, the aromaticity concept is broader and possibly fuzzier than ever.__\\ \\ Source : [[https://pubs.rsc.org/en/content/articlehtml/2023/sc/d3sc90075d|Chem. Sci., 2023, 14, 5542-5544]]{{:oa_padlock_grn.png?16}}

Some research groups are now suggesting that the concept can only be understood by calling on quantum [[content:physics:quantum_physics:entanglement|superpostion]] ideas. The details of which, however, are yet to be agreed upon.

>While both aromaticity and its counterpart, antiaromaticity, are associated with the delocalization of electrons between nonorthogonal atomic orbitals, they lack a universally accepted and comprehensive definition.\\ \\ Source :[[https://arxiv.org/pdf/2307.00672.pdf|arXiv:2307.00672]]{{:oa_padlock_grn.png?16}}