Reactivity descriptors local

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... 

FIGURE 23.5 Profiles of different local reactivity descriptors (electrophilic attack) along the path of the gas phase SN2 substitution F + CH3—Fb —> Fa—CH3 + Fb. Profiles of energy and bond order are also shown. (Reprinted from Chattaraj, P.K. and Roy, D.R., J. Phys. Chem. A, 110, 11401, 2006. With permission.)... 

Introduces and analyzes the usefulness of local reactivity descriptors such as Fukui, shape, and electron localization functions... 

The book comprises chapters on bonding, interactions, reactivity, dynamics, toxicity, and aromaticity as well as fundamental aspects of DFT. Several chapters are minireviews of the key global and local reactivity descriptors and their variations under different perturbations. 

The utility of global and local reactivity descriptors to predict chemical reactivity and C- versus O-alkylation has been investigated for the case of lithium enolates.298... 

Chandrakumar, K.R.S., and Pal, S., DFT and local reactivity descriptor studies on the nitrogen sorption selectivity from air by sodium and calcium exchanged zeolite-A, Colloids Surf. A - Physicochemical Eng. Aspects, 205, 127-138, 2002a. 

Pal, S. and Chandrakumar, K.R.S., Critical study of local reactivity descriptors for weak interactions qualitative and quantitative analysis of adsorption of molecules in the zeolite lattice, J. Am. Chem. Soc., 122, 4145 4153, 2000. 

Deka, R.Ch., Roy, R.K. and Hirao, K. (2004) Local reactivity descriptors to predict the strength of Lewis acid sites in alkali cation-exchanged zeolites. Chem. Phys. Lett., 389, 186-190. 

Popular qualitative chemical concepts such as electronegativity [1] and hardness [2] have been widely used in understanding various aspects of chemical reactivity. A rigorous theoretical basis for these concepts has been provided by density functional theory (DFT). These reactivity indices are better appreciated in terms of the associated electronic structure principles such as electronegativity equalization principle (EEP), hard-soft acid-base principle, maximum hardness principle, minimum polarizability principle (MPP), etc. Local reactivity descriptors such as density, Fukui function, local softness, etc., have been used successfully in the studies of site selectivity in a molecule. Local variants of the structure principles have also been proposed. The importance of these structure principles in the study of different facets of medicinal chemistry has been highlighted. Because chemical reactions are actually dynamic processes, time-dependent profiles of these reactivity descriptors and the dynamic counterparts of the structure principles have been made use of in order to follow a chemical reaction from start to finish. 

In this chapter, we present different global and local reactivity descriptors vis-a-vis the associated electronic structure principles for analyzing structures, properties, reactivity, bonding, interactions, and dynamics in the contexts of various physicochemical processes such as molecular vibrations, internal rotations, chemical reactions, aromaticity, stability of isomers, ion-atom collisions, atom-filled interactions, solvent effect, etc. Global reactivity descriptors are presented in Section 2, whereas Section 3 provides their theoretical basis. Section 4 delineates the local reactivity descriptors. Electronic structure principles associated with electronegativity and hardness are given in Sections 5 and 6, respectively. Section 7 presents the reactivity... 

Abstract Quantitative structure-activity relationship (QSAR) models are generated for biological activity and toxicity in terms of global and local reactivity descriptors within a conceptual density functional theory framework. Possible anticancer activity of two new metal-borane clusters is analyzed. 

In addition to the various conceptual DFT-based global reactivity descriptors, the local reactivity descriptors also provide valuable insights in determining chemical reactivity patterns. The various local reactivity indices like electron density (p(r)), Fukui function (/(r)), local softness (s(r)), local hardness ( (r)), and philicity (ft)(r)) help to assess the response of a particular atomic site in a molecule during a chemical attack. 

In this connection the usefiilness of local reactivity descriptors for understanding drug metabolism of neonicotinoids, the electrophilic Fukui function of THIAM 6 was investigated (20). 

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. 

The reactivity descriptors described above have been defined for an atom or a molecule as a whole and accordingly they are termed as global reactivity descriptors. In order to analyze the site selectivity in a molecule several local reactivity descriptors or their condensed-to-atom variants have been thought of. 

The density p(r) is a local reactivity descriptor which may be defined as ... 

One of the most important intramolecular local reactivity descriptors is the Fukui function which is defined... 

Brief Outline of Global and Local Reactivity Descriptors.392... 

BRIEF OUTLINE OF GLOBAL AND LOCAL REACTIVITY DESCRIPTORS... 

The local reactivity descriptor, Fukui function (FF), measures the change in electron density at a given point when an electron is added to or removed from a system at constant v(f). It may be written as... 

Keywords Conceptual density functional theory Global reactivity descriptors Local reactivity descriptors HSAB Electric field effect Local HSAB... 

Kar R, Chandrakumar KRS, Pal S (2007) The Influence of electric field on the global and local reactivity descriptors reactivity and stability of weakly bonded complexes. J Phys Chem A lll(2) 375-383... 

---