Spectrophotometric Studies of Charge Transfer Complexes of 8-Hydroxyquinoline with Iodine in Different Solvents

Abstract

The formation of 8-hydroxyquinoline-iodine charge transfer complex was confirmed by UV-Vis spectrophotometric method in carbon tetrachloride, dichloromethane, chloroform, ethanol and methanol. A change in UV-Vis spectrum of iodine is observed upon addition of 8-hydroxyquinolinein these solvents, where as the appearance of new bands support the formation of charge transfer complexes. The spectrum obtained from the complex of 8-hydroxyquinoline and iodine show different absorption bands at different wavelength for different solvents. The ratio of the charge transfer complex formed was determined from Job’s Continuous Variation method. The spectrum obtained from the complex of 8-hydroxyquinolineand iodine shows absorption bands at 365 nm for carbon tetrachloride, 360 nm for dichloromethane, 358 nm for chloroform, 355 nm for ethanol and 290 nm for methanol. Parameters like dissociation energy, transition energy of the complex and ionization potential of the donor were calculated from their . The values of these parameters were found to be increased from the less polar solvent, carbon tetrachloride to the more polar solvent methanol. The complex formed is relatively stable in less polar solvents than more polar solvents.

Keywords: 8-hydroxyquinoline, iodine, UV-Vis spectrophotometer.