Solvent and Substituent Effects on the Ultraviolet-Visible Absorption Spectra of Azo Dyes

Abstract

The effects of solvents, including polymeric substrates, and substituentson the absorption spectra of 4,4'-donor acceptor- substituted azo dyes were studied. The position of the intense, visible charge-transfer band was dependent on the di electric properties of the solvent ; a linear relationship was found between observed and calculated frequency shifts. Spec tral behavior obtained for the dyes in polymeric solvents was consistent with that obtained for the dyes in nonpolymeric solvents. The relationship between dye structure and solvent effects was also determined. Shifts in absorption maxima with substitution in positions insulated from the conjugated chromophoric system were consistent with Taft polar-substituent constants; the effects of such substituents were, therefore, primarily inductive in nature.

Keywords

Azo dyes polar and nonpolar substrates. Intramolecular charge transfer dipolar interactions spectral shifts solvent effects substituent effects. Absorption spectra thin-layer chromatography.

Get full access to this article

View all access options for this article.

References

Bayliss, N.S. , The Effect of the Electrostatic Polarization of the Solvent on Electronic Absorption Spectra in Solution, J. Chem. Phys. 18, 292-296 (1950).

Bayliss, N.S. and McRae, E.G. , Solvent Effects in Organic Spectra: Dipole Forces and the Franck-Condon Principle, J. Phys. Cliem. 58, 1002-1006 (1954).

Birnbaum, P.O. , Linford, J.H. , and Style, D.W.G. , The Absorption Spectra of Azobenzene and Some Derivatives, Trans. Faraday Soc. 49, 735-744 (1953).

Bridgeman, I. and Peters, A.T. , Synthesis and Electronic Spectra of Some 4-Aminoazobenzenes , J. Soc. Dyers Colourists 86, 519-524 (1970).

Buraway, A. , Studies in the Light Absorption of Organic Compounds. Part VIII. Azo Compounds , J. Chem. Soc. 1937 1865 (1937).

Dilling, W.L. , The Effect of Solvent on the Electronic Transitions of Benzophenone and Its o- and p-Hydroay Derivatives, J. Org. Chem. 31, 1045-1050 (1966).

Godfrey, M. and Murrell, J.N. , Substituent Effects on the Electronic Spectra of Aromatic Hydrocarbons. III. An Analysis of the Spectra of Amino- and Nitro-benzenes in Terms of the Localized-Orbital Model, Proc. Royal Soc. (London), Ser. A. 278, 71-90 (1964).

Jaffé, H.H. , Yeh, S.J. , and Gardner, R.W. , The Electronic Spectra of Azohenzene Derivatives and Their Conjugate Acids , J. Mol. Spectrosc. 2, 120-136 (1958).

Kosower, E.M. , The Effect of Solvent on Spectra. I. A New Empirical Measure of Solvent Polarity: Z-Values, J. Amer. Chem. Soc. 80, 3253-3260 (1958).

10.

Kosower, E.M. , The Effect of Solvent on Spectra. II. Correlation of Spectral Absorption Data With Z-Values, J. Amer. Chem. Soc. 80, 3261-3267 (1958).

11.

McRae, E.G. , Theory of Solvent Effects on Molecular Electronic Spectra Frequency Shifts, J. Phys. Chem. 61, 562-572 (1957).

12.

McRae, E.G. , Solvent Effects on Merocyanine Spectra, Spectrochim . Acta 12, 192-210 (1958).

13.

Porter, G. and Suppan, P. , Primary Photochemical Processes in Aromatic Molecules, Trans. Faraday Soc. 61, 1664-1673 (1965 ).

14.

Taft, R.W. , "Steric Effects in Organic Chemistry," New York , Wiley, pp. 607-610, 1956.

15.

Yoshida, Z. and Takabayashi, F. , Electronic Spectra of Monosubstituted Anthraquinones and Solvent Effects, Tetrahedron 24, 933-943 (1968).

16.

Hodgman, C. D. , editor, " Handbook of Chemistry and Physics," 41st ed., Cleveland, Ohio, Chemical Rubber Publishing Co., p. 2515, 1960.