Limiting the Growth of Water-Soluble, Monolayer-Protected Quantum Dots.

The growth and solubility of quantum dots (QDs) are important factors that must be examined before these nanoparticles are incorporated into a variety of potential applications. In this work, monolayer-protected CdSe QDs surrounded by water-soluble thiols were prepared using various cadmium salts. The use of a variety of cadmium salts did not have a significant impact on the spectral properties of the CdSe QDs.

Temperature-dependent quantized double layer charging of monolayer-protected gold clusters.

This paper describes low-temperature voltammetry of purified hexanethiolate-coated monolayer-protected Au140 clusters (C6 MPCs). Lowered temperatures enhance the resolution of quantized double layer (QDL) charging peaks in differential pulse voltammetry (DPV) observations. As many as 13 resolved peaks are seen in illustrative voltammetry at 263 K in CH2Cl2 solvent, and the concept of voltammetric peak capacity is introduced.

Quantized double-layer charging of highly monodisperse metal nanoparticles.

We describe unprecedented resolution of electrochemically observed quantized double layer (QDL) charging, attained with use of reduced solution temperatures and with an annealing procedure that produces hexanethiolate monolayer protected gold clusters (C6 MPCs) with a high level of monodispersity in charging capacitance, C(CLU). The spacing DeltaV = e/C(CLU) on the electrochemical potential axis between one electron changes in the electronic charge of nanoscopic metal particles is determined by their effective capacitance C(CLU). The high monodispersity of the C6 MPCs with Au(140) cores facilitates (a) detailed rotated disk and cyclic voltammetric measurements, (b) simulation of QDL waveshapes based on assumed reversible, multivalent redox-like behavior, (c) determination of nanoparticle diffusion rates, and (d) observation of as many as 13 changes in the MPC charge state, from MPC(6-) to MPC(7+).