Engineered Au Core@Prussian Blue Analogous Shell Nanoheterostructures: Their Magnetic and Optical Properties

We report a new approach for the synthesis of multifunctional Au core@Prussian Blue analogous (PBA) shell nanoheterostructures that involves PBA shell growth on the surface of cyanide-stabilized gold nanoparticles. It permits the assembly of Au@KNi^II [Fe^II (CN)₆ ] core@shell and Au@KNi^II [Fe^II (CN)₆ ]@KNi^II [Cr^III (CN)₆ ] core@shell@shell heterostructures with well-defined and size-controlled gold cores and PBA shells. These heterostructures exhibit tunable size- and shape-dependent magnetic and optical properties: (i) the surface plasmon resonance band position and intensity mainly depend on the PBA shell thickness, and (ii) the magnetic properties (the transition temperature, the coercivity, and magnetic regime) depend in a complex manner on the thickness as well as the particular morphology of the magnetic shell.