Preparation, Characterization, Redox, and Photoinduced Electron‐Transfer Properties of the NIR‐Absorbing N‐Ferrocenyl‐2‐pyridone BODIPYs

Abstract

Mono‐ and di‐(N‐ferrocenyl‐2‐pyridone)‐containing BODIPYs were prepared using a set of ferrocene‐enamine cyclization reactions. The target compounds were characterized by UV‐Vis, NMR, and mass spectrometry, while their redox properties were probed by the electrochemical, spectroelectrochemical, and chemical oxidation methods. Redox properties of the di‐(ferrocenyl)‐containing BODIPY are suggestive of a lack of electronic coupling between the two ferrocene groups. Oxidation of the ferrocene(s) in the target BODIPYs results in their observable fluorescence, while transient absorption spectroscopy data indicate fast electron‐transfer from ferrocene donor to the photoexcited BODIPY acceptor. Density functional theory (DFT) and time‐dependent DFT (TDDFT) methods were used to elucidate electronic structures of the organometallic BODIPYs and confirm the presence of the low‐energy metal‐to‐ligand charge‐transfer states in the NIR region.