Abstract
The absorption and fluorescence spectral properties 1,5-diaminoanthraquinone (DAAQ) have been investigated in a series of organic solvents of different polarity and in aqueous solutions with Ho/ pH /H–in the range -10 to 17. The Stokes shifts of DAAQ are correlated with various solvent polarity scales. The better correlation of Stokes shifts of DAAQ with ET(30) indicates the predominance of hydrogen bonding interactions over dipolar interactions. The study also reveals that the fluorescence of DAAQ dication is red shifted on protonation. The abnormal fluorescence of DAAQ is found to be due to large solvent relaxation in polar medium. The acidity constants for various prototropic reactions in Soand S1states are determined and discussed.
Highlights
Solvents effects on physical or chemical processes are usually studied by means of empirical parameters[1], to determine the type of interaction force that predominance in the solvent effect
The absorption maxima of DAAQ is red shifted in all the solvents, except water
Compared to cyclohexane the absorption maximum is blue shifted in water
Summary
Solvents effects on physical or chemical processes are usually studied by means of empirical parameters[1], to determine the type of interaction force that predominance in the solvent effect. The absorption maxima of DAAQ is red shifted in all the solvents, except water. A blue shift relative to cyclohexane is generally observed for all amino compounds in water. The fluorescence maxima of DAAQ are red shifted from cyclohexane to water.
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