Hitoshi Fukushima

A GRAM SCALE SYNTHESIS OF MONODISPERSED SILVER NANOPARTICLES CAPPED BY CARBOXYLATES AND THEIR LIGAND EXCHANGE

In this paper, we report a simple yet powerful synthetic method for obtaining monodispersed silver nanoparticles by direct thermal decomposition of two materials — one is silver acetate as a source of the metal core and the other is myristic acid as a capping agent. The reaction was performed at 250°C, the boiling point of myristic acid, without additional solvent. The nucleation and growth of the particles were monitored by dynamic light scattering in order to optimize the reaction time. By this simple procedure, we could obtain uniformly sized Ag nanoparticles with the average diameter of 4.8 ± 0.1 nm. Although the particles were synthesized at high temperature, the ligand exchange between myristates and alkanethiolates can be achieved at room temperature. Significant characteristics of Ag nanoparticles attributed to localized surface plasmons were investigated.

Fluorescence Probing of Self-Assembled Monolayer with Terphenyl-Derivatized Disulfides

The formation processes of and molecular ordering in self-assembled monolayers were investigated by fluorescence probing with p-terphenyl chromophores binding to disulfides at the o- or p-positions. In mixtures with dodecanethiol, the derivatized disulfides formed ordered monolayers. As compared with the broad monotonic fluorescence spectra in solutions, their emission bands were split into distinct peaks upon chemisorption on gold substrates due to intermolecular interactions between adjacent terphenyl groups. Their emission peak positions were interpreted in terms of the exciton coupling of various dimeric terphenyl configurations in the monolayers depending on the o- and p-isomeric structures.