Homogeneous photocatalysis by transition metal complexes in the environment

Complexation of the Fe(III) and Fe(II) sulphates with diphenyl-4-amine barium sulphonate (DAS) Synthesis, thermogravimetric and spectroscopic studies

“…. In this study, however, it was impossible to attribute a band to this species in the UV-Vis spectra [9,[11][12][13]. Figure 2 shows the infrared spectra of Ba-DAS, and Fe 2 DAS 4 and Fe 3 DAS 6 complexes.…”

“…The maximum of the spectra is close to k = 246 nm, normally attributed to the transition of p electrons and associated to the displacement of double bond inside the aromatic rings. The small difference found between the k max of the Ba-DAS and the Fe(II) complexes and the band intensities indicate that the ions are slight affected by the DAS ligand [9,11]. The reactions destined to the ligand photo degradation catalyzed by Fe(III) use k = 365 nm for the excitation of the photo active species FeOH 2?…”

“…The addition of alcohol inhibits these processes. This care, the sulphate ion, the excess of surfactant, the inert atmosphere and the temperature and pH (\5) control minimize the action of the oxidizing species [5,9,[11][12][13].…”

“…The excited ligand radical L • 1 in general reaches its most stable oxidation state through an intermolecular process that reduces the Fe(III) to Fe(II). Radiations with k [ 330 nm are enough for the ligand excitation [9][10][11][12][13].…”

“…acts as a photodegradation starter through the internal transfer of electrons, which photo reduces the Fe(OH) 2? species, producing the Fe(II) ions and the • OH radical [9,11,12].…”