STM/STSによる金サブナノクラスターの電子構造の研究

2003年分子構造総合討論会, 2003年9月24日-27日, 京都テルサ(京都), 1Pp092本研究は、文部科学省のナノテクノロジー総合支援プロジェクトの支援を受けて実施されたものである

STM/STSによる金サブナノクラスターの電子構造の研究

2003年分子構造総合討論会, 2003年9月24日-27日, 京都テルサ(京都), 1Pp092本研究は、文部科学省のナノテクノロジー総合支援プロジェクトの支援を受けて実施されたものである

STM/STSによる金サブナノクラスターの電子構造の研究

2003年分子構造総合討論会, 2003年9月24日-27日, 京都テルサ(京都), 1Pp092本研究は、文部科学省のナノテクノロジー総合支援プロジェクトの支援を受けて実施されたものである

STM/STSによる金サブナノクラスターの電子構造の研究

2003年分子構造総合討論会, 2003年9月24日-27日, 京都テルサ(京都), 1Pp092本研究は、文部科学省のナノテクノロジー総合支援プロジェクトの支援を受けて実施されたものである

STM/STSによる金サブナノクラスターの電子構造の研究

2003年分子構造総合討論会, 2003年9月24日-27日, 京都テルサ(京都), 1Pp092本研究は、文部科学省のナノテクノロジー総合支援プロジェクトの支援を受けて実施されたものである

Ion Transport across Biological Membranes by Carborane-Capped Gold Nanoparticles

Carborane-capped gold nanoparticles (Au/carborane NPs, 2-3 nm) can act as artificial ion transporters across biological membranes. The particles themselves are large hydrophobic anions that have the ability to disperse in aqueous media and to partition over both sides of a phospholipid bilayer membrane. Their presence therefore causes a membrane potential that is determined by the relative concentrations of particles on each side of the membrane according to the Nernst equation. The particles tend to adsorb to both sides of the membrane and can flip across if changes in membrane potential require their repartitioning. Such changes can be made either with a potentiostat in an electrochemical cell or by competition with another partitioning ion, for example, potassium in the presence of its specific transporter valinomycin. Carborane-capped gold nanoparticles have a ligand shell full of voids, which stem from the packing of near spherical ligands on a near spherical metal core. These voids are normally filled with sodium or potassium ions, and the charge is overcompensated by excess electrons in the metal core. The anionic particles are therefore able to take up and release a certain payload of cations and to adjust their net charge accordingly. It is demonstrated by potential-dependent fluorescence spectroscopy that polarized phospholipid membranes of vesicles can be depolarized by ion transport mediated by the particles. It is also shown that the particles act as alkali-ion-specific transporters across free-standing membranes under potentiostatic control. Magnesium ions are not transported

Toward an Atomic-Level Understanding of Size-Specific Properties of Protected and Stabilized Gold Clusters

Metal clusters consisting of fewer than 100 atoms (diameter <2 nm) are highly promising as a new class of building units for functional materials because of their novel and size-dependent properties. Nevertheless, basic and applied studies of metals clusters have been hampered by the lack of specific guidelines for design and precise synthetic methods. This account surveys recent investigations of gold clusters focusing on our effort toward an atomic-level understanding and control of their size-specific properties. We have developed a size-controlled method for synthesizing gold clusters protected by ligands, stabilized by polymers, and supported on solids. Remarkable size-effects on stabilities and various properties including catalysis were observed. Their mechanisms are discussed based on fundamental knowledge of bare gold clusters in the gas phase

Isolation and structural characterization of magic silver clusters protected by 4-(tert-butyl)benzyl mercaptan

Small silver clusters (average diameter of 1.2 nm) protected by 4-(tert-butyl)benzyl mercaptan (BBSH) were converted to stable, monodisperse clusters (2.1 nm) by a ripening process with excess amount of BBSH. Multiple characterizations of the isolated magic clusters revealed an approximate chemical composition of Ag∼280(SBB)∼120