| 15926840 |
Balasubramanian R, Guo R, Mills AJ, Murray RW: Reaction of Au (55)(PPh (3))(12) Cl (6) with thiols yields thiolate monolayer protected Au (75) clusters. J Am Chem Soc. 2005 Jun 8;127(22):8126-32.
This paper describes the reaction of the phosphine-protected Au nanoparticle Au (55)(PPh (3))(12) Cl (6) (1, "Au55") with hexanethiol (2) and other thiols. The voltammetry of the reaction product 2 displays a well-defined pattern of peaks qualitatively reminiscent of Au (38) nanoparticles, but with quite different spacing (0.74 +/- 0.01 V) between the potentials of initial oxidation and reduction steps (electrochemical gap). Correction of this "molecule-like" gap for charging energy indicates a HOMO-LUMO gap energy of about 0.47 V. Voltammetry of the products (3 and 4) of reaction of 1 with C (3) H (7) SH and PhC (2) H (4) SH, respectively, is similar. Laser desorption/ionization mass spectrometry (LDI-MS) shows that 2 contains a high proportion of a core mass in the 14-15 kDa range, which is proposed to be Au (75). UV-vis spectra of 2-4 are relatively featureless, similar to previous reports of thiolate-protected Au (75) nanoparticles. HPLC analysis of 2 shows a Au (75) content of ca. 73%; the electrochemical purity estimate is also high, about 55%. Combining the mass spectrometric result with thermogravimetric analysis of 2 leads to a preliminary formulation Au (75)(SC (6) H (13))(40). This Au (75) synthesis complements a previous Brust-type synthesis and is unusual in the apparent provocation in the reaction of an increase in core size. |
7(0,0,1,2) |