| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2004: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2003: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
This research project aims at synthesizing complexes of polyoxometalates with transition metal ions, analyzing their crystal structures, and then examining the physicochemical properties that are specific to their structures. First, the magnetic properties of [Cu_2(OH)_2(OH_2)_6][Cu_2(OH_2)_8][V_<10>O_<28>]-4(CH_3)_2CO, which was first synthesized and characterized by the investigator, were investigated. The compound has two pairs of Cu^<2+> cations on the two sides of the [V_<10>O_<28>]^<6-> core, which are separated by 2.89 Å and 3.37 Å, respectively. The unpaired electrons of these pairs were not coupled and each Cu^<2+> atom works as an independent spin center. Second, double salts of [V_<10>O_<28>]^<6-> with Cu^<2+> and NH_4^+, K^+ or Rb^+ were synthesized and their crystal structures were determined. In these crystals, a water molecule coordinating to the cation supports a hydrogen atom on the [V_<10>O_<28>]^<6-> core via hydrogen bond and stabilizes a monoprotonated species, [HV
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_<10>_O<28>]^<5->. In these crystals, the precise location of the protons on the monoprotonated decavanadate anion was first determined unambiguously. Also, the structure determination of [SiW_<11>O_<39>]^<8-> crystallized with Na^+ and guanidinium cations revealed that the compound exhibits a novel screw structure of [SiW_<11>O_<39>]^<8-> linked by Na^+ cation, although transition metals were not incorporated into the compound. Its structure indicated a possibility that it would show non-linear optical properties and thus pulsed laser light with the wavelength of 800 nm was irradiated, resulting in the observation of second harmonic generation. In parallel with these studies, the investigator has installed and upgraded diffractometers at two synchrotron facilities : SPring-8 and Photon Factory of High Energy Accelerator Research Organization. These efforts have profited the precise structure analyses of abovementioned NLO active silicotungstate crystals as well as the structural elucidation of the molecular growth and intermolecular condensation of mixed valence molybdenum giant clusters with nanometer sized ring shape. Less
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