Identification of O-bridge iron perfluorophthalocyanine dimer and generation of high-valent diiron-oxo species for the oxidation of organic pollutants

- ESI-MS assisted by pyridine ligands was used to identify FePcF16-O-FePcF16.
- DFT analysis indicated the HOMO and LUMO energy levels of FePcF16-O-FePcF16 and Fe(IV)O.
- The main active species in CBZ degradation were Fe(IV)O.
- CBZ degradation products were finally transformed to four small molecule acids.

Phthalocyanine has been used widely as an oxidation catalyst, e.g., in wastewater treatment. It has become important and necessary to study phthalocyanine derivatives, to understand the potential effect they may have. Despite the fact that phthalocyanine dimers are easy to generate, such complexes have been ignored as catalysts. We prepared O-bridged iron perfluorophthalocyanine dimers (FePcF16-O-FePcF16). Ultraviolet-visible, X-ray diffractometry, X-ray photoelectron spectroscopy, density-functional theory analysis and electrospray ionization-mass spectrometry technology assisted by pyridine ligands have been used to identify the structure of FePcF16-O-FePcF16. Carbamazepine selected as a model pollutant could be effectively oxidized in the system with FePcF16-O-FePcF16 and H2O2. Electron paramagnetic resonance data indicated an active center that was different from OH in the Fenton reaction. Electrospray ionization-mass spectrometry detected the generation of high-valent diiron-oxo species, which implies that carbamazepine degradation was accomplished by the attack of FeIVOFeIVO in the FePcF16-O-FePcF16/H2O2 system. Thus, we identified an O-bridge iron perfluorophthalocyanine dimer and proposed a catalytic mechanism. These results may provide a novel explanation for the oxidative mechanism.

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