Electron photoejection from dianion of an expanded phthalocyanine

Abstract

Photoelectron ejection from the dianion of pentabenzotriazasmaragdyrin (PBTAS) which is an expanded phthalocyanine, is observed using femtosecond transient absorption spectroscopy. The PBTAS dianion was produced by chemical reduction using excess cobaltocene as a reductant, which was confirmed by their steady-state absorption spectrum as compared to the absorption spectrum obtained by electrochemical reduction, and characterized by magnetic circular dichroism (MCD). Upon photoexcitation of the PBTASdianion, the generation of a radical anion was confirmed by the characteristic absorption peaks that are observed at 950 and 1000 nm. The radical anion was relaxed to form a dianion with a time constant of 0.7 ps.