Electron affinities topology

A common feature of the various methods that we have developed for the calculation of electronic effects in organic molecules is that they start from fundamental atomic data such as atomic ionization potentials and electron affinities, or atomic polarizability parameters. These atomic data are combined according to specific physical models, to calculate molecular descriptors which take account of the network of bonds. In other words, the constitution of a molecule (the topology) determines the way the procedures (algorithms) walk through the molecule. Again, as previously mentioned, the calculations are performed on the entire molecule. 

C60 shows an extremely facile reduction profile and there is evidence for the addition of up to 12 electrons to the molecule. The prediction that C60 will exhibit an exceptionally high electron affinity and that the molecule will add up to 12 electrons under suitable conditions (Haddon et al. 1986a) seems to be borne out by the experimental results. Rehybridization plays an important role in determining the electronic structure of the fullerenes and it is the combination of topology and rehybridization which together account for the extraordinary ability of C60 to accept electrons. 

An analj is of the interactions of ions with ligands leads to valuable information which is difficult to obtain otherwise. Important data for resolving the dynamical structure of the protonated methane cation CHs arises from the infra-red spectra of CH5 (H2)n [45,61]. The topology of shells is projected on the properties of bare ions. The process of the consecutive electron photodetachment from the central anion indicates the existence of the well developed shell structure of complexes. The theoretically predicted electronic affinities for O AXn clusters calculated for theoretical structures of complexes agree with the known measured values (Table 3) [62,63]. The ionization potential of CHa Arn clusters is little... 

The concept of topological resonance energy was introduced to provide a relative measure of aromaticity <77JA1692>. In a newer approach, the absolute hardness, or HOMO-LUMO gap, as the measure of aromaticity is defined to be in the ionization potential of the species minus its electron affinity. The parameters of the absolute hardness and a related relative hardness for (152) are consistent with the high reactivity of this compound <89JA737l>. 

In order to perform controlled and reversible movements and to behave as a machine, the envisaged molecular system should have a mobile and a fixed component one of the components should be redox active and the oxidized and reduced states should have almost comparable stability and should be connected by a reversible, and possibly fast, electron transfer process. The two oxidation states should display a different topological affinity with respect to the other component, so that a redox change can induce a modification of the topology of the whole molecular system, generating an intramolecular motion. The occurrence of fast and reversible movements also requires that the interaction between the mobile and the fixed part is based on... 

Mukherjee, S., Mukherjee, A. and Saha, A. (2005) QSAR modeling on binding affinity of diverse estrogenic flavonoids electronic, topological and spatial functions in quantitative approximation. 

Several research groups have also used theoretical methods in an effort to understand the activating and deactivating effects of the substituents in S Ar reactions. For example, Galabov and coworkers have developed a computational approach for determining electrophile affinity, Ea, as a measure to determine arene reactivity and positional selectivity in S Ar reactions [36]. Other recent approaches to this problem include the development of reactive hybrid orbital analysis [37], the topological analysis of electron localization function [38], the calculations of electrostatic potentials at the arene carbons [39], and several other methods. A comprehensive summary of this area is beyond the scope of this chapter however, the interested reader may consult one of the recent reviews of this topic [40]. 

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