MECHANISM OF PHOTOINDUCED REDOX REACTIONS IN AQUEOUS-SOLUTIONS OF [FE(BPY)(CN)4]2-

The mechanism of redox reactions by UV excitation of [Fe(bpy)(CN)4]2- in aqueous solutions has been investigated by continuous photolysis, laser kinetic spectroscopy and pulse radiolysis. The hydrated electrons formed have been shown to be scavenged by [Fe(bpy)(CN)4]2-of ground state to form [Fe(bpy)(CN)4]3- characterized by its absorption spectrum and reactions or by other electron scavengers (NO3-, MV2+) to yield oxidizing (.NO2) and reducing (.MV+) intermediates, respectively. It has been pointed out that methylviologen radical is also produced by electron transfer reaction from [Fe(bpy)(CN)4]3-, and disappears in reactions with the ground state iron(II) and iron(III)complexes. The yield of reduced methylviologen, the species wich can transform the light to chemical energy, can be optimized based on the kinetic model presented.