Connecting and combining rules of aromaticity. Towards a unified theory of aromaticity

Defining rules of aromaticity: a unified approach to the Hückel, Clar and Randić concepts.

The molecular structure of any system may be unambiguously described by its adjacency matrix, A, in which bonds are assigned entry a(ij) = 1 and non-bonded pairs of atoms entry a(ij) = 0. For π-electron-containing conjugated hydrocarbons, this matrix may be modified in order to represent one of the possible Kekulé structures by assigning entry 1 to double bonds and entry 0 to single bonds, lead...

Shannon entropy as a new measure of aromaticity, Shannon aromaticity.

Based on the local Shannon entropy concept in information theory, a new measure of aromaticity is introduced. This index, which describes the probability of electronic charge distribution between atoms in a given ring, is called Shannon aromaticity (SA). Using B3LYP method and different basis sets (6-31G**, 6-31+G** and 6-311++G**), the SA values of some five-membered heterocycles, C(4)H(4)X, a...

Aromaticity Alexandru

Aromaticity has been lately in the center of attention of chemists with books [1-3], journal special issues [4-10], reviews [11, 12], and publications (these are too numerous to cite). The discoveries of fullerenes, nanotubes, nanocones, and nanotori as well as the recent techniques for obtaining graphene sheets with monatomic thickness and astounding properties have enlarged our views about th...

Aromaticity of Carbon Nanotubes

Carbon nanotubes are composed of cylindrical graphite sheets. Both nanotubes and graphite sheets are benzenoid derivatives composed of sp2 carbon atoms arranged in a hexagonal pattern. Therefore both systems are aromatic. The extent of the aromatic character of a molecule G (here benzenoids) can be explained in terms of the number of possible Kekulé structures in G. In this work the Kekulé stru...

Spherical aromaticity of fullerenes.