Switching of inter-valence charge transfer in stimuli-responsive bis(ferrocenyl)porphyrin

Abstract

Stimuli-responsive 5,15-bis(ferrocenyl)-10,20-bis(mesityl)porphyrin (BFP) was synthesized and used to demonstrate the ON/OFF switching of inter-valence charge transfer (IVCT) between ferrocene terminals. IVCT was observed at 829 nm after the protonation of BFP by gaseous hydrogen chloride. The protonation of the porphyrin core oxidizes one of the two ferrocene units which leads to the PBFP having a mixed valence state. This was confirmed by Mössbauer spectroscopy. The ON/OFF switching of IVCT was demonstrated by the protonation and deprotonation of BFP successively with gaseous hydrogen chloride and ammonia.