Color changes accompanying one-electron reduction and oxidation of the azo dyes

The primary products of one-electron oxidation and reduction of the azo dye, 4-N,N-diethylaminoazobenzene, have been spectroscopically characterized in cryogenic matrices. The radical anion of the dye is characterized by the absorption band at 645 nm in 2-methyltetrahydrofuran matrix and at 595 nm in alcoholic matrices. The radical cation exhibits weak absorption bands at 601, 659, 721 and 791 nm in 2-chlorobutane matrix. The reactivity of the radical ions has been investigated by means of pulse radiolysis in solution at room temperature and in cryogenic glasses. The transient products formed upon one-electron reduction and oxidation of the dye are characterized by the electronic absorption spectra and color changes of the solution.