Electronic spectral behaviour of some new hydroxy azocoumarin derivatives

The spectral behaviour of six new hydroxy azocoumarin compounds has been Investigated in solution. The bands appearing in the UV and Visible regions are assigned to the possible electronic transitions. It is evident that azocoumarin compounds are found to exist mainly in the azo form, while 6-[2-hydroxy-6-aminonaphthyl-1-azo] coumarin exist in the azo-hydrazone tautomeric equilibrium. The solvatochromic behaviour of the azo compounds is investigated through studying their spectra in pure and mixed organic solvents of different characteristics. The longer wavelength band displayed by the azocoumarin in DMF solution is assigned to an intermolecular CT transition.