UV-Induced Formation of [Fe(bpy)3]2+ Complex and its Confinement into Silica Fine Particles

Silica fine particles in a single or sub-micrometer regime, containing FeCl₃ and 2,2-bipyridine (bpy), were prepared by utilizing reverse micellar method. Formation of tris-bpy iron(II) ([Fe(bpy)₃]²⁺) complex was induced in the silica fine particles by UV irradiation at 365 nm. The starting micellar solution was obtained by an injection of 0.04 cm³ HCl aqueous solution into 5 cm³ tetraethyl orthosilicate (TEOS)/cyclohexane (2 cm³/3 cm³) mixed solution containing 4–14 vol% of nonionic surfactant, polyoxyethylene(5) nonylphenyl ether (NP-5). Size of the silica particles was regulated by the concentration of NP-5.