One-step synthesis of gold nanoparticles using azacryptand and their applications in SERS and catalysis.

A new aqueous-phase method for the preparation of stable gold nanoparticles by using 1,4,7,10,13,16,21,24-octaazabicyclo[8.8.8]hexacosane (azacryptand) as both reductant and stabilizer is reported. Reduction of HAuCl(4) with azacryptand at room temperature yields nano-sized particles within a short time. The obtained gold nanoparticles have been characterized by UV-vis spectroscopy, transmission electron microscopy, and X-ray diffraction. Comparison of FT-IR spectra of azacryptand before and after reaction revealed that azacryptand molecules reduce gold ions as the amino moieties in the molecules are oxidized to imino groups. The prepared gold nanoparticles show efficient surface-enhanced Raman scattering properties and can effectively catalyze reduction of 4-nitrophenol by sodium borohydride in aqueous solution.