Combined Density Functional Theory and Molecular Dynamics Study On the Design and Application of Super- Alkali/Halogen and Analysis of Reaction Mechanism

Abstract

Density functional theory (DFT), an alternative to ab-initio wave-function based electronic structure method and Conceptual density functional theory (CDFT), a method extracted from chemically relevant concepts and principles from DFT, have been used to analyze different reaction mechanism and the properties, associated energies, stabilities of various special molecules like superalkalis, superhalogens, superacids, etc. The dynamical properties and potential application of some of these molecules were further investigated using molecular dynamics (MD) techniques. The thesis is segregated into nine chapters. Chapter 1 provides a short account of the current status of research in the area of different types of superalkalis, superhalogens, superacids, frustrated Lewis pairs (FLP), etc., and their potential applications. A brief note on the methodologies employed to design such molecules, analyze their properties, and study different reaction mechanism has been furnished. Chapter 2 deals with the design of heterocyclic superalkalis and superhalogens as well as organometallic superalkalis from the stable aromatic molecular systems like C6H6, B3N3H6, Au3 etc. Chapter 3 foretells the designing of superacids in terms of Brønsted and Lewis perspectives from the more reactive aromatic superhalogen molecules. In Chapter 4 an attempt has been made to design the frustrated Lewis pairs by replacing the ligand in Lewis acid part of popularly used FLP, tris(pentafluorophenyl) borane (TPFPB) with the superhalogen to explore its efficiency to activate the H2 molecule compared to the conventionally used FLP. Further, a new class of boron-based anion receptor for Li-ion battery (LIB) electrolytes has been designed using the superhalogen ligands. Chapter 5 unfolds the transport properties and solvent properties of some of the designed boron-based anion receptor additives and identifies their efficacy as compared to the popular anion-receptor additive, TPFPB for the use of LIB electrolyte. Chapters 6 to 9 deal with various reactions mechanism studies. The ground state and first excited state gas phase double proton transfer reaction mechanism was studied in formic acid dimer in the light of reaction force, reaction electronic flux, and its different components in Chapter 6. Chapter 7 provides a relation between pKa and activation energy for double proton transfer reaction in inorganic acid dimer. The reaction involved in the CO2 activation with the help of a small cluster B3N3 was studied extensively in Chapter 8. In Chapter 9, the chemical reaction involved in the alkylation process of Zintl cluster was analyzed with different CDFT descriptors.