The one-step synthesis and spectroscopic characterizations of size-controlled silver nanoparticles are described. The transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric-mass analysis (TGA-MS) and X-ray photoelectron spectroscopy (XPS) techniques were used to characterize the decanoate-protected silver nanoparticles. TEM analysis showed that spherical nanoclusters of 7.52 +/- 0.57 nm were produced. Furthermore, the particle sizes are uniform with a narrow size distribution. For all samples, Ag 3d(5/2) and 3d(3/2) components appeared at 368.5 and 374.5 eV, respectively, in the XPS spectrum; these values compare very well with the typical values of carboxylate-protected Ag nanoparticles. A thermal analysis mass spectrometer was used to analyze the desorption behavior of decanoate-protected nanoparticles. From the desorption maximum temperatures of 181 and 263 degrees C, activation energies of 27.2 and 32.2 kcal mol(-1) for the desorption processes in the Ag MPCs were obtained, assuming a first-order reaction and using a pre-exponential factor of 1 x 10(13) s(-1). A specific resistivity of 6.097 microOmega cm for the silver metal film (0.7 microm) on a Si wafer can be produced simply by thermal annealing of an Ag monolayer-protected clusters film under an atmosphere of 90% N(2)-10% H(2) at 300 degrees C for 1 h.

We report the electrical transport characteristics of a series of molecular wires, fc-C≡C-C6H4-SAc (fc = ferrocenyl; Ac = acetyl) and AcS-C6H4-C≡C-(fc)n-C≡C-C6H4-SAc (n = 2, 3), consisting of multiple redox-active ferrocenyl centers. The self-assembled monolayers of these molecular wires on Au surfaces were comprehensively characterized by electrochemistry and conductive atomic force microscopy techniques. Characterization of the wires revealed that electron transport is made extremely efficient by the organometallic redox states. There is a strong electronic coupling between ferrocenyl moieties, and superior electron-transport ability exists through these semirigid molecular wires. Standard rate constants for the electron transfer between the electrode and the ferrocenyl moieties were measured for the monolayers by a potential-step chronoamperometry technique. The electron conduction through the molecular wires was estimated using the monolayers as a bridge from the Au(111) metal surface to the gold tip of a conductive atomic force microscope (CAFM). Using the CAFM, Coulomb blockade behavior arising from the capacitive charging of the multinuclear redox-active molecules was observed at room temperature. The conductance switching was mediated by the presence of various ferrocenyl redox states and each current step corresponded to a specific redox state.

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