Chiroptical spectroscopic structural determination of organic, inorganic and biomolecules

Abstract

The significance of being able to reliably establish the structure of chiral molecules is manifested through the recognition that different enantiomers and diastereomers of the same compound can have vastly different effects with respect to a specific function. A portion of this Dissertation describes the configurational and conformational analysis of chiral molecules via experimental and theoretical applications of chiroptical spectroscopic methods. Three chiroptical spectroscopic techniques, Vibrational Circular Dichroism (VCD), Electronic Circular Dichroism (ECD), and Optical Rotatory Dispersion (ORD), complement each other in a quest for an unambiguous structural determination. A comparison between experimentally obtained and theoretically predicted chiroptical spectroscopic properties allows the stereochemical elucidation of chiral species. The first tandem application of the three methods has been demonstrated through structural investigations of several chiral organic and inorganic molecules: C2–symmetric spiroselenurane (Chapter 2), trinickel(II) complex of dypiridylamine (Chapter 3), 2,2'-diphenyl-[3,3'-biphenanthrene]-4,4'-diol (Chapter 4), a set of sulfoxide-containing chiral molecules (Chapter 5), and t-butyl-phenyl-phosphinoamidate (Chapter 6). Chapter 7 of the Dissertation evaluates the utility of ECD for the analysis of ORD in dimethyl tartrate using KK transform. The last three chapters of the Dissertation pertain to VCD based investigations on carbohydrates (Chapter 8), homopolynucleotides (Chapter 9), and tetrapeptide (Chapter 10). These chapters not only evaluate the applicability of the VCD method for elucidating the structures of these classes of biomolecules, but also introduce, film state measurements which, when applicable, can greatly aid the VCD-based structural analysis.