Theoretical Analysis of the Reactivity of Carbon Nanotubes: Local Versus Topological Effects

In carbon materials the mobile π electrons are situated in topologically different circumstances at edge sites, and their π electronic states, essentially controlled by the network structure of sp2 carbon, may be significantly affected. In this work, we derived topological indications about the reactivity of carbon nanotubes and fullerenes with the hydroxyl radical (OH•), the most important oxidizing species in the troposphere. For each molecular structure, we computed the local softness, the Mulliken charges of the reacting carbons of (n,n) and (n,0) clusters, and their Huckel-type aromaticity rules, as an index to determine topologically independent sites and predicting a certain grade of reactivity of the nanotube and fullerenic carbon atoms. Using local softness, closely related to the energy gap, it was possible to separate the periodical nanotubes in three families according to their reactivity. A connection between the reactivity index ΔE and the topology was established by means of the Fukui integrated function. It resulted that for (n,0) clusters, odd n implies aromaticity, whereas even n, non-aromaticity; (n,n) clusters are in any case non-aromatic. For a better understanding of some experimental results, we also discussed how edge effects can influence topological reactivity due to the increment of the number of benzene rings in some cluster arrangements

The Bond Analysis Techniques (ELF and Maximum Probability Domains) Application to a Family of Models Relevant to Bio-Inorganic ChemistryApplications of Density Functional Theory to Biological and Bioinorganic Chemistry

Electron Localization Function (ELF) and Maximum Probability Domain (MPD) analyses have been applied to model metal–porphyrins and show compatible and complementary results. ELF basins are quite different from MPDs, but are a necessary starting point for optimizing them. The analyses of the bond between the metal and porphyrin do not show significant differences between nontransition and transition metals. In all the cases considered, we find signatures characteristic of essentially ionic bonds

Electron Localization Function and Maximum Probability Domains analysis of semi-ionic oxides crystals, surfaces and surface defects

Maximum Probability Domain (MPD) analysis has been recently applied to pure covalent and ionic crystals. The present study is devoted to a first MPD analysis of semi ionic crystals, Silicon Oxide, Aluminum Oxide and Titanium Oxide. These crystals are involved in important catalytic and photo-catalytic processes occurring on their surfaces. For this reason the study has been performed on bulk crystal and on surface slab models. Also surface neutral oxygen vacancy, the F-0 surface defect, has been considered. The Electron Localization Function (ELF) analysis has also been performed, due to its holistic approach to electronic structures. (C) 2015 Published by Elsevier BM