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Charge-Transfer Interactions of Nicotine with Chloranil: Solvent Effects UV-Visible Spectrophotometric Study

Maher M. Girgis ; Chemistry Department, Faculty of Science, Assiut University, Assiut, Egypt (P. O. Box: 161, Assiut)

Sažetak

UV-visible spectrophotometric studies on the interaction of nicotine with chloranil in cyclohexane, dioxane, benzene, chloroform and dichloromethane solutions at 25 °C demonstrate the formation of charge-transfer (CT) complexes. A new broad band begins to grow in time on the longer wavelength side of the characteristic absorption bands of the constituents. At equilibrium, the new band position depends on the polarity of the solvent used. In EtOH, MeOH and DMSO solutions, a new absorption spectra are immediately formed after mixing. The position of the new spectra is not affected by the solvent polarity. The solvation of the CT-complex immediately causes complete ionization of the neutral complex. It has been found that acetone acts as intermediate between the non-ionizing and ionizing solvents in which absorptions corresponding to the ions are observed simultaneously with the intermolecular CT-absorption. The stability constants and the molar absorptivities of the complexes formed have been calculated assuming the formation of 1 :1 complexes. Experimental results indicate that the stability constant of the complex formed and its type (neutral or ionic) depends greatly on the dielectric constant of the solvent used.

Ključne riječi

Hrčak ID:

137414

URI

https://hrcak.srce.hr/137414

Datum izdavanja:

10.3.1990.

Posjeta: 669 *