Chlorophyll a π‐Cation Radical as Redox Mediator in Superoxide Dismutase (SOD) Mimetics. Issue 4 (15th January 2021) - Orzeł, Łukasz
Abstract: The extensive speciation of copper(II) chloride in organic solvents varies with concentration, temperature, pressure and oxygen content, providing the ability to switch between different chlorophyll transmetalation pathways. We found that one of them is exceptionally suitable for the formation and stabilisation of the chlorophyll π‐cation radical. This is due to unique redox cycling, which is coupled to the generation and transformation of various reactive oxygen species. In the presence of a proton donor, our system shows behavior which resembles that of superoxide dismutase (SOD). Regardless of light, chlorophyll acts as an electron transfer mediator. Abstract : Generation of the π‐cation radical of chlorophyll a is observed in organic media in the presence of O2 and particular Cu(II) salts. The stability of this radical, as observed spectroscopically, is assigned to a redox cycling controlled by the copper speciation in the presence of O2 and proton donors. Under such conditions, regardless of light, chlorophyll a can act as the electron‐transfer mediator, which mimics, in a way, the superoxide dismutase catalytic activity.