Synthesis, Characterization, and Electronic Properties of Metalloporphyrins Annulated to Exocyclic Imidazole and Imidazolium Rings

Abstract

Abstract meso ‐Tetraarylporphyrin complexes (M = Ni, Cu, Zn, H 2 ) fused to an imidazole ring across two neighboring β‐pyrrolic positions were synthesized through a cyclization reaction between β,β′‐diaminoporphyrins and formic acid or trimethyl orthoformate under acidic conditions. Two synthetic procedures were used to obtain the corresponding porphyrin N , N′ ‐dimethylimidazolium salts derivatives: alkylation of the imidazole nitrogen atoms with iodomethane and the cyclization reaction between the porphyrin bearing two neighboring β‐ N ‐methyl groups and trimethyl orthoformate in the presence of ammonium hexafluorophosphate. The electrochemical properties of these porphyrins annulated to an imidazole/imidazolium ring have been investigated by cyclic and rotating disk voltammetry.