Orientations of polyoxometalate anions on gold nanoparticles

Cryogenic transmission electron microscopy of polyoxometalate-protected gold nanoparticles reveals that the Preyssler ion, [NaP5W30O110]14–, lies “face down” with its C5 axis perpendicular to the gold surface, while the Finke–Droege ion, [P4W30Zn4(H2O)2O112]16–, is “tilted”, with its long axis close to 60° from the normal to the surface.