Porphyrin for possessing low valence state of metal center

Abstract We discovered that metal center confined in the porphyrin structure can process lower valence state (LV) via reversible photoinduced electron transfer in both singlet and triplet states, which are confirmed by X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS), electron spin resonance (ESR) and density functional theory (DFT) calculations. More importantly, this controlling strategy was hardly influenced by the electronegative properties of surrounding porphyrin structures, at the same time, it can be widely applied to various metal elements such as Zn, Cu, Ni, Co, Fe. This work provides a new vision to fabricate and deeply understand the metal center with lower valence state from single atom level.