Optical studies of polyvinylpyrrolidone reduction effect on free and complex metal ions

Polyvinylpyrrolidone (PVP) reduction effect on free and complex Ag+ and Au3+ ions was studied from optical measurements by adding a metal precursor (K-30), commonly used as a stabilizer, to PVP. It was found that PVP has a strong reduction effect on free ionic metal, such as Ag+ ion in AgNO3, but much weaker on complex ionic metals, AuCl4- in HAuCl4 and Ag(NH3)(2)(+) in Ag(NH3)(2)OH. This is explained based on the coordinative field of polar group in PVP molecules.