PHOTODISSOCIATION OF A (MU-PEROXO)(MU-HYDROXO)BIS[BIS(BIPYRIDYL) COBALT(III)] COMPLEX - A TOOL TO STUDY FAST BIOLOGICAL REACTIONS INVOLVING O-2

Upon photolysis at 355 nm, dioxygen is released from a (mu-peroxo)(mu-hydroxo)bis[bis(bipyridyl)cobalt(III)] complex in aqueous solutions and at physiological pH with a quantum yield of 0.04. The [Co(bpy)(2)(H2O)(2)](2+) (bpy = bipyridyl) photoproduct was generated on a nanosecond or faster time scale as determined by time-resolved optical absorption spectroscopy. A linear correspondence between the spectral changes and the oxygen production indicates that O-2 is released on the same time scale, Oxyhemoglobin was formed from deoxyhemoglobin upon photodissociation of the (mu-peroxo) (mu-hydroso)bis[bis(bipyridyl)cobalt(III)] complex, verifying that dioxygen is a primary photoproduct. This complex and other related compounds provide a method to study fast biological reactions involving O-2, such as the reduction of dioxygen to water by cytochrome oxidase.