UV/Vis, IR and 1H NMR spectrophotometric studies of some bisazo-dianil compounds based on bis-(hydroxy, formyl) phenylazo phenylene and anthranilic acid.

The electronic absorption spectra of some bisazo-dianils are studied in organic solvents of different polarity and in buffer solutions of varied pH. The different absorption bands are assigned to the corresponding electronic transitions, the solvent effect on the CT band energy is also discussed. The spectral study in buffer solutions is utilized for the determination of the pKa of the phenolic OH-groups.