Global aromaticity at the nanoscale
Top Cited Papers
- 20 January 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in Nature Chemistry
- Vol. 12 (3), 236-241
- https://doi.org/10.1038/s41557-019-0398-3
Abstract
Aromaticity can be defined by the ability of a molecule to sustain a ring current when placed in a magnetic field. Hückel’s rule states that molecular rings with [4n + 2] π-electrons are aromatic, with an induced magnetization that opposes the external field inside the ring, whereas those with 4n π-electrons are antiaromatic, with the opposite magnetization. This rule reliably predicts the behaviour of small molecules, typically with fewer than 22 π-electrons (n = 5). It is not clear whether aromaticity has a size limit, or whether Hückel’s rule extends to much larger macrocycles. Here, we present evidence for global aromaticity in porphyrin nanorings with circuits of up to 162 π-electrons (n = 40); aromaticity is controlled by changing the constitution, oxidation state and conformation. Whenever a ring current is observed, its direction is correctly predicted by Hückel’s rule. The largest ring currents occur when the porphyrin units have fractional oxidation states.Keywords
Other Versions
This publication has 37 references indexed in Scilit:
- Fluorenyl Based Macrocyclic PolyradicaloidsJournal of the American Chemical Society, 2017
- Bicyclic Baird-type aromaticityNature Chemistry, 2017
- Aromatic and antiaromatic ring currents in a molecular nanoringNature, 2016
- [62]Tetradecaphyrin and Its Mono‐ and Bis‐ZnII ComplexesChemistry – A European Journal, 2016
- Benchmarking Density Functional Theory Approaches for the Description of Symmetry Breaking in Long Polymethine DyesThe Journal of Physical Chemistry C, 2016
- Stable [48]-, [50]-, and [52]Dodecaphyrins(1.1.0.1.1.0.1.1.0.1.1.0): The Largest Hückel Aromatic MoleculesChemistry – A European Journal, 2015
- Organic Mixed‐Valence Compounds: A Playground for Electrons and HolesAngewandte Chemie, 2011
- Renaissance of Annulene ChemistryChemical Reviews, 2006
- Spectroscopy of Nanoscopic Semiconductor RingsPhysical Review Letters, 2000
- Beyond the Cyanine Limit: Peierls Distortion and Symmetry Collapse in a Polymethine DyeJournal of the American Chemical Society, 1997