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

Abstract

Abstractmeso‐Tetraarylporphyrin complexes (M = Ni, Cu, Zn, H2) 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.