Synthesis and characterization of ultrasmall rhenium nanoparticles (1.5 nm)

Abstract Ultrasmall rhenium nanoparticles were prepared by a reduction of rhenium trichloride with sodium borohydride in water capped with the tripeptide glutathione. The particles were approximately spherical with an average diameter of 1.5 nm and had a high degree of internal crystallinity as shown by transmission electron microscopy and X-ray powder diffraction. They were well dispersible in water as differential centrifugal sedimentation (DCS), 1 H-NMR DOSY spectroscopy (nuclear magnetic resonance–diffusion-enhanced spectroscopy), and small-angle X-ray scattering (SAXS) showed. 1 H-NMR spectroscopy and 13 C-NMR spectroscopy confirmed that glutathione was attached to the nanoparticle via the terminal thiol group of cysteine. Upon heating in oxygen, the nanoparticles were converted into dirhenium heptoxide which evaporated above 360 °C.