Spectroscopic investigation of the chargetransfer equilibria between a few ndonors and acceptors

Abstract

The thesis quotSpectroscopic investigation of the charge-transfer equilibria between a few n-donors and o-acceptorsquot consists of four chapters. The chapter 1 (INTRODUCTION) gives a general outline of the molecular complexes and enlists their principal features as the appearance of a highly intense charge-transfer band with very large molar extinction coefficient, the differences in polarity of donor, acceptor and complex, the dependence on the medium, the influence of ionization potential and electron affinity on complex formation, the dependence of thermodynamic parameters on nature and strength of bonding in the complex, etc. The basic ideas of the electron-transfer theory of molecular complexes, developed by Mulliken and Hush have been incorporated bringing out the components governing donor-acceptor interactions. The different types of donors and acceptors, liable to form CT complexes, have been described and the role played by solvents in stabilizing CT interactions has been stressed. The chapter concludes with a description of the methodologies used in the study of CT equilibria with emphasis on spectrophotometric and conductometric techniques, and on characterization methods such as X-ray diffraction study, etc. The chapter 2 (SPECTROPHOTOMETRIC STUDY) commences with a review of the importance of the CT complexes between n-donors and o-acceptors. The difficulties in using multifunctional donors and acceptors have been briefly indicated and the importance of hexamethylene tetramine (HMT) in CT equilibria study is spelt out. The chapter gives a complete, brief description of the procedure adopted for spectroscopic investigation of the interactions among HMT, triethylamine (TEA) and diethylamine (DEA) as n-donors and iodine, bromine and iodine-monochloride as o-acceptors in various solvents, viz., n-Hexane, cyclohexane, carbontetrachloride, chloroform, dichloromethane and 1:1 mixtures of cyclohexane-dichloromethane, carbontetrachloride-dichloromethane, n-hexane-chloroform and cyclohexane-chloroform. The...