DFT Based Studies on Bioactive Molecules

Ambrish Kumar Srivastava, Neeraj Misra

• Verlag: Bentham Science Publishers
• Jahr: 2021
• ISBN:
  9789814998369
• Thema: Biological Sciences
• Thema: Biophysics

This book is a guide for researchers, academics and experimentalists who wish to explore density functional theory (DFT) on selected molecular systems. The salient features of the book include concise and complete coverage of DFT on biologically active molecules, a basic guide to DFT for beginners followed by its computational application using a powerful Gaussian program. Subsequently, discussions on synthetic compounds, amino acids, and natural products have been offered by the authors for the benefit of the reader. The book also features an exclusive chapter on the quantum theory of atoms in molecules and is supplemented by an appendix on the Gaussian output for methane. Key Features: · basic introduction of density functional theory· practical introduction to Gaussian program· interpretation of input and output files· explanation of calculated parameters· examples of several bioactive molecules (syenthetic and natural)· correlation between theory and experiments· exploration of the hydrogen bonds· appendix covering Gaussian outputs for methane· beginner friendly text· references at the end of each chapter DFT Based Studies on Bioactive Molecules is a suitable handbook for academics, students and researchers who are learning the basic biophysics and computational chemistry of bioactive molecules with reference to DFT models.

DFT Study on Some Synthetic Compounds: (2,6), (2,4) and (3,4) Dichloro Substituted Phenyl-N-(1,3-thiazol-2-yl) Acetamides

Ambrish Kumar Srivastava^{1, *}, Neeraj Misra²

¹ Department of Physics, Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur, Uttar Pradesh, India

² Department of Physics, University of Lucknow, Lucknow, Uttar Pradesh, India

Abstract

In this chapter, we present and discuss DFT study on three dichloro substituted (1, 3-thiazol-2-yl) acetamides; 26DTA, 24DTA and 34DTA using the B3LYP/6-31+G(d,p) method. We focus on the need of scaling the normal modes of vibrations and test two scaling schemes on 26DTA. We analyze their performance by comparing the scaled values against FTIR data. Subsequently, a detailed comparative study on the spectroscopic properties of 24DTA and 34DTA has been performed using a better scaling scheme. In addition, the NBO analysis is employed to explain the coordination ability of molecules and several electronic parameters are obtained to describe their chemical reactivity. This chapter is expected to provide the first flavor of the real application of DFT on biologically active molecules.

Keywords: Acetamide, B3LYP, Coordination ability, DFT, Electron parameters, FTIR, HOMO, LUMO, NBO, NPA, Scaling equation, Scaling factor, Vibrational spectra.

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^* Corresponding author Ambrish Kumar Srivastava: Department of Physics, Deen Dayal Upadhyaya Gorakhpur University, Gorakhpur, Uttar Pradesh, India; Tel: ?????; Fax: ?????; E-mail:[email protected] and E-mail:[email protected]

INTRODUCTION

Acetamide based heterocycles having nitrogen and sulphur atoms, form a distinct group of pharmacologically important compounds with an amide bond similar to that between amino acids in proteins (Chapter 4 will specifically address unusual amino acids). Several natural products and drug compounds contain such heterocyclic moieties [1, 2], including the derivatives of thiazole, which have several biological activities [3, 4]. For instance, the thiazoles have been used in the development of drugs for the cure of several diseases [5^-12], fibrinogen receptor antagonists with antithrombotic activity [13] an inhibitor of bacterial DNA gyrase B [14]. It is, therefore, desirable to explore some novel compounds based on the thiazole ring. In this chapter, we present DFT based studies on three molecules, namely, 2-(2,6-Dichlorophenyl)-N-(1,3-thiazol-2-yl) acetamide [26DTA], 2-(2,4-Dichlorophenyl)-N-(1,3-thiazol-2-yl) acetamide [24DTA], and 2- (3,4-Dichlorophenyl)-N-(1,3-thiazol-2-yl) acetamide [34DTA]. The results [15^-17] were obtained by the B3LYP functional and 6-31...