Entrapment of Organic Molecules within Metals: Dyes in Silver

We proved the feasibility of entrapment of organic molecules within a metal. Specifically, Congo red, Safranin-O, and thionine were entrapped in metallic silver, obtained through the aqueous reduction of silver cations with sodium hypophosphite. Not only were these water-soluble molecules entrapped, but so was the hydrophobic Sudan III by solubilizing it with sodium dodecyl sulfate. It was proven that the molecules remain intact by the entrapment procedure and that the entrapment is within cages and narrow pores formed by Ag crystallites which aggregate into bulk powder of low porosity. Furthermore, it was proven that a population of nonleachable entrapped molecules is accessible to reaction with external reagents which diffuse inside through the metal pore network.