Electrochemistry as an Attractive and Effective Tool for the Synthesis and Immobilization of Porphyrins on an Electrode Surface

Magnesium(II) 10‐phenyl‐5,15‐p‐ditolylporphyrin is easily and cleanly transformed by electrolysis. A nitro group is first introduced at the free meso position by anodic substitution. Hydrogenation into the amine is then carried out electrocatalytically under ambient conditions with water as a hydrogen supplier. The synthesized porphyrin under the nickel(II) form can be covalently grafted onto a platinum electrode by electrochemical reduction of the diazonium cation, generated in situ by a reaction of the nickel(II) aminoporphyrin with sodium nitrite and trifluoroacetic acid. The electrosynthesized thin film gives an electrochemical response typical of a porphyrin material. Films grown under our conditions have a maximum surface coverage of approximately 5×10−10 mol cm−2. The modified electrode exhibits a reproducible electrochemical behavior and a good level of stability over potential cycling and exposition to air. Being choosy: Selective approaches based on electrochemistry have been developed to yield different porphyrins. The final synthesized porphyrin is covalently attached to the electrode surface through the electroreduction of the corresponding diazonium generated in situ in organic media (see figure; RE, CE, WE=ref, counter and working electrode, respectively). The results demonstrate that electrochemistry is an efficient alternative tool for the synthesis of designed porphyrins and their use in surface modification.