Summary of Research Project Results under JSPS FY2003
"Research for the Future Program"

1.Research Institution Okazaki National Research Institutes
2.Research Area Physical and Engineering Sciences
3.Research Field Photoscience
4.Term of Project FY 1999 - FY 2003
5.Project Number 99P01201
6.Title of Project Photochemical Synthesis of Super-Clusters and their Optical Diagnostics: the Way to Making Single Molecular Magnets

7.Project Leader
Name Institution,Department Title of Position
Nobuyuki,Nishi Okazaki National Research Institutes, Institute for Molecular Science Professor

8.Core Members

Names Institution,Department Title of Position
Toshihiro,Yamase Tokyo Institute of TechnologyCChemical Resources Laboratory Professor
Katsuya, Inoue Okazaki National Research Institutes, Institute for Molecular Science Associate Professor

9.Summary of Research Results

1.   Photochemical Generation of Super Cluster Molecules: Super cluster molecules are generated with aid of electrostatic interactions between ion-paired (+E-) radicals. Magnetic cluster molecules, (C5H5) nVnO6 are typical examples. UV irradiation of isopolyoxomolybdates in aqueous solutions containing electron donors produced high-nuclearity mixed- valence species as a result of reduction self assembly processes based on the dehydrative condensation at [MoVO5(OH)]sites produced photochemically in the polyoxomolybdate lattice. Thus tire-shaped molybdenum blues, [Mo142O432H28 (H2O)58]12- are formed as molecular crystals in which each ring is stacked forming an array of nanotubes.
2.   Development of novel single-domain molecular or molecule-based magnets, examination of their practical use: Some of new single molecule magnets were synthesized, while all these molecules exhibited properties as magnets only at very low temperatures and found to be not so much useful at room temperature. We decided to make new molecule-based single-domain magnets with good properties as room-temperature nano-magnets. The system is gtransition metal acetylide compoundsh with π-d four-centered ferromagnetic interactions among two transition metal atoms and a (C≡C)2- molecule. MnC2, FeC2, CoC2 and NiC2 are found to be ferromagnetic and the former three compounds provided room-temperature magnets. Rod-shaped CoC2 nanocrystals exhibited a cohesive force of 650 Oe at 300K. The crystals smaller than several nanometers behaved only as super-paramagnetic, while electron beam irradiation on such polycrystalline acetylides produced carbon-encapsulated nano-metals. This phenomenon provides us an electron beam manufacture method for air-stable carbon-encapsulated metal dots and wires.
3.   We invented a new type of a mass spectrometer with an liquid-gas interface with a liquid jet nozzle, a solute-coating rotating drum, and laser desorption exit. This apparatus allow us to mass-analyze solute super-clusters or protein molecules suspended in solution without contaminating oxygen or any third body.
4.   We also succeeded to synthesize transparent chiral-molecular-magnets with Tc values higher than 40K. With these crystals, one can modulate the intensity of near ultraviolet light with changing magnetic field continuously.

10.Key Words
(1)super-cluster   (2)transition-metal acetylides   (3)photochemical synthesis
(4)single-domain magnet   (5)grafite-skinned iron nano-crystals   (6)hetero-polyacids
(7)room-temperature nano-magnet   (8)chiral molecular magnet   (9)magnetic light modulation element