Biomaterial Database

Aromaticity rules for cycles with arbitrary numbers of half-twists. 2006

Patrick W Fowler, and Henry S Rzepa

Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK. P.W.Fowler@sheffield.ac.uk

A simple proof is given that the Hückel aromaticity rules generalise to cycles with an arbitrary number of half-twists, T; addition/removal of half-twists two at a time preserves all eigenvalues and degeneracies, so that closed-shell aromatic systems occur at pi-electron counts 4N+ 2, and antiaromatic at 4N for even T, and vice versa for odd T.

UI	MeSH Term	Description	Entries
D008956	Models, Chemical	Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.	Chemical Models,Chemical Model,Model, Chemical
D008968	Molecular Conformation	The characteristic three-dimensional shape of a molecule.	Molecular Configuration,3D Molecular Structure,Configuration, Molecular,Molecular Structure, Three Dimensional,Three Dimensional Molecular Structure,3D Molecular Structures,Configurations, Molecular,Conformation, Molecular,Conformations, Molecular,Molecular Configurations,Molecular Conformations,Molecular Structure, 3D,Molecular Structures, 3D,Structure, 3D Molecular,Structures, 3D Molecular
D006841	Hydrocarbons, Aromatic	Organic compounds containing carbon and hydrogen in the form of an unsaturated, usually hexagonal ring structure. The compounds can be single ring, or double, triple, or multiple fused rings.	Aromatic Hydrocarbon,Aromatic Hydrocarbons,Hydrocarbon, Aromatic
D000465	Algorithms	A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.	Algorithm
D015394	Molecular Structure	The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.	Structure, Molecular,Molecular Structures,Structures, Molecular