Photooxidation of anthracene under visible light with metallocarboxyphenylporphyrins

In this work, three novel carboxyphenylporphyrins (TcPP-M, M= H, Cu y Zn) have been synthesized and their efficiency in the photooxidation of anthracene under visible light (l> 500 nm) through generation of oxygen singlet (1O2) has been evaluated. The presence of 1O2 was evidenced by Electron Paramagnetic Resonance (EPR), where it reacts with 2,2,6,6-tetramethyl-4-piperidone-N (TEMP) to produce 2,2,6,6-tetramethyl-4-piperidone-N-oxyl radical (TEMPO). The catalytic results indicated that the incorporation of the metal in the porphyrin ring strongly affects their efficiency on the anthracene oxidation. The TcPPH showed a higher photonic efficiency (31%) in the anthracene conversion than TcPPZn (13%) and TcPPCu (9%). This result may be related to the disruption of the planarity of the porphyrin ring. Finally the formation of anthraquinone and oxanthrone was detected as the oxidation products in the anthracene oxidation with 1O2.