It has been reported that, the UV spectra of monophenylazo
compounds differ from those of monophenylhydrazones The azo compounds generally show two absorption bands at 410–400 and
290–300 nm corresponding to n–* and –* transitions, respectively
[17]. The monophenylhydrazones, on the other hand, show
three intense bands in the 220–228, 250–280 and 330–390 nm
regions [18].