Conceptual density functional theory chemical reactivity

Conceptual density functional theory (DFT) [1-7] has been quite successful in explaining chemical bonding and reactivity through various global and local reactivity descriptors as described in the previous chapters. The Fukui function (FF) [4,5] is an important local reactivity descriptor that is used to describe the relative reactivity of the atomic sites in a molecule. The FF [4,5] is defined as... 

From the theoretical point of view, the electrophilicity concept has been recently discussed in terms of global reactivity indexes defined for the ground states of atoms and molecules by Roy et al.18 19. In the context of the conceptual density functional theory (DFT), a global electrophilicity index defined in terms of the electronic chemical potential and the global hardness was proposed by Maynard et al.20 in their study of reactivity of the HIV-1 nucleocapsid protein p7 zinc finger domains. Recently, Parr, Szentp ly and Liu proposed a formal derivation of the electrophilicity, co, from a second-order energy expression developed in terms of the variation in the number of electrons.21... 

Conceptual density functional theory has been quite successful in providing quantitative definitions for popular qualitative chemical concepts like electronegativity , hardness and electrophilicity . It has also been found to be useful in providing firm theoretical bases for the associated electronic structure principles. Various global and local reactivity descriptors " have played an important role in analyzing bonding, reactivity, stability, interactions and aromaticity in a variety of many-electron systems as well as a host of their physico-chemical properties. 

Although known for almost a couple of centuries there exists no direct measure of aromaticity mainly because it is neither an experimental observable nor it is a theoretically defined quantity. In this chapter various types of aromatic systems with a special emphasis to all-metal aromatic clusters have been discussed. Different indirect aromaticity measures have been analyzed with special emphasis to some chemical reactivity based aromaticity indices within a conceptual density functional theory... 

In the last three decades, density functional theory (DFT) has been extensively used to generate what may be considered as a general approach to the description of chemical reactivity [1-5]. The concepts that emerge from this theory are response functions expressed basically in terms of derivatives of the total energy and of the electronic density with respect to the number of electrons and to the external potential. As such, they correspond to conceptually simple, but at the same time, chemically meaningful quantities. 

Fig. 1 The workflow of structure-activity relationships involving conceptual and computational density functional theory through molecular frontier information (e.g., HOMO and LUMO), which are primarily employed as electronegativity (x) and chemical hardness (rf) indices and are then combined to form chemical power (x/2 y) and electrophilicity (x l2rj) reactivity measures. These values are correlated with observed biological and ecological activity (A) to provide the QSAR models (A ) to finally produce ligand progress curves (L) that provide a hierarchy of chemical reactivity principles involved in biological activity within a given DFT computational framework and species of interest...

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