SYNTHESIS AND CHARACTERIZATION OF HYDROPHOBIC, ORGANICALLY-SOLUBLE GOLD NANOCRYSTALS FUNCTIONALIZED WITH PRIMARY AMINES

We report on the synthesis and characterization of 25-70 Angstrom diam eter amine-capped gold nanocrystals. In particular, we show how these particles can be prepared by a simple procedure and confirm the partic le composition (including the identity of the amine surface passivant) through several materials characterization techniques that include in frared spectroscopy, nuclear magnetic resonance spectroscopy, ultravio let-visible spectroscopy, mass spectroscopy, X-ray photoelectron spect roscopy, transmission electron microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetric analysis, and el emental analysis. All physical characterizations are consistent with a charge-neutral amine/gold surface interaction described by a weak cov alent bond. The stability of the particles appears to be largely kinet ic, rather than thermodynamic, in nature. Comparison of these nanocrys tals to amines adsorbed onto bulk Au surfaces indicates that the stabi lity of the nanocrystal/amine system is a finite-size effect.