Bispalladium(II) Complexes of di‐p‐Pyrirubyrin Derivatives as Promising Near‐Infrared Photoacoustic Dyes

Abstract The insertion of palladium(II) into di‐ p ‐pyrirubyrin results in mutually convertible bimetallic complexes. Post‐synthetic functionalization of one of them yielded bispalladium(II) dioxo‐di‐ p ‐pyrirubyrin and, after demetallation, dioxo‐di‐ p ‐pyrirubyrin, introducing for the first time the α,β′‐pyridin‐2‐one unit into the macrocyclic frame. Bispalladium(II) di‐ p ‐pyrirubyrin 6 , bispalladium(II) dioxo‐di‐ p ‐pyrirubyrin 9 , and dioxo‐di‐ p ‐pyrirubyrin 10 absorb and emit light around 1000 nm and are characterized by high photostability. Thus, they are promising candidates for near‐infrared photoacoustic dyes, ideally targeting ( 9 ) the wavelength of Yb‐based fiber lasers. The incorporation of an α,β′‐pyridine moiety into expanded porphyrins opens a highly interesting area of research due to the attractive optical and coordination properties of the resulting molecules.