A new method of preparing alkanethiol-protected gold nanoparticals

Abstract

In a new two-phase system (tetrahydrofuran/saturated NaCl aqueous solution) monolayer protected clusters (MPCs) were prepared. The AuCl₄ ⁻ anion in saturated electrolyte aqueous solution was transferred into the organic phase of tetrahydrofuran by tetra-n-butylammonium bromide ((C₄H₉)₄NBr) and was reduced quickly by sodium borohydride in the presence of alkanethiol. The functionalized MPCs were characterized by solubility, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray (EDX) analysis and UV-vis spectroscopy. Electrochemical measurements of MPCs in CH₂ Cl₂ exhibited 7 pairs of reversible voltammetric waves within the potential range of −1.0 to 1.0V (vs Ag/AgCl), which was ascribed to the quantized capacitance charging of nanoparticle double layers. All the results show that the new preparing method is feasible.

Keywords

chemical preparation / monolayer protected cluster / quantized charging

References

[1] Yu H-h, Jiang D-s. Gold Nanoparticulate Thin Films Fabricated by The Electrostatic Self-Assembly Process. J. Wuhan. Univ. of Tech.-Mater. Sci. Ed., 2002, 17(1): 38-41.

[2] Li Y-x, An J-m, Zhang Y-l, Li Q. Study on The Method for Measuring Nano-Displacement. J. Wuhan. Univ. of Tech.-Mater. Sci. Ed., 2001, 16(3): 70-72.

[3] Lehn J-M. Perspectives in Superamolecular Chemistry-From Molecular Recognition Towards Molecular Information Processing and Self-organization. Angew. Chem., 1990, 29(11): 1304-1319.

[4] Willner I. Photoswitchable Biomaterials: An Route to Optobioelectronic Systems. Acc. Chem. Res., 1997, 30(9): 347-356.

[5] Brust M, Walker M, Bethell D, Schiffrin J D, Whyman R. Synthesis of Thiol-derivatised Gold Nanoparticles in Two-phase Liquid-liquid System. J. Chem. Soc. Chem. Commun., 1994, 7: 801-802.

[6] Leff D V, Heath P C, Gelbart W M. Thermodynamic Control of Gold Nanocrystal Size: Experiment and Theory. J. Phys. Chem., 1995, 99(18): 7036-7041.

[7] Hostetler M J, Wingate J E, Zhong C-Z, . Alkanethiolate Gold Cluster Molecules with Core Diameters from 1.5 to 5.2 nm: Core and Monolayer Properties as a Function of Core Size. Langmiur, 1998, 14(1): 17-30.

[8] Macus Y. Extraction of Alkali Halides from Their Aqueous Solution by Crown Ethers. J. Phys. Chem., 1978, 82(11): 1246-1254.

[9] Bellamy L J. The Infrared Spectra of Complex Molecules, 1954, London: Wiley. 392-392.

[10] Osawa M, Matsada N, Yoshii K, Uchida I. Charge Transfer Rosonance Roman Process in Surface-Enhanced Roman Scattering fromp-Aminothiophenol Adsorbed on Silver Herzberg—Teller Contribution. J. Phys. Chem., 1994, 98(48): 12702-12707.

[11] Alvarze M M, Khoury J T, Schauff T G, . Optical Absorption Spectra of Nanocrystal Gold Molecules. J. Phys. Chem., 1997, 101(19): 3706-3712.

[12] Mulvaney P. Surface Plasmon Spectroscopy of Nanosized Metal Particles. Langmuir, 1996, 12(3): 788-800.

[13] Bohren C F, Huffman D R. Absorption and Scattering of Light by Small Particles, 1983, Wuhan: Wiley. 178-178.

[14] Ingram R S, Hostetler M J, Murrary R W, . First 28 kDa Alkanethiolate-Protected Au Clusters Give Analogous Solution Electrochemistry and STM Coulomb Staircases. J. Am. Chem. Soc., 1997, 119(39): 9279-9280.

[15] Chen S, Murray R W, Feldberg S W. Quantized Capacitance Charging of Monolayer-Protected Au Clusters. J. Phys. Chem. B, 1998, 102(49): 9898-9970.