Toshihiro Yamase

Inframolecular Energy Transfer and Mn4 + Luminescence in Polyoxometallomanganate Lattices

Photoexcitation of the oxygen (O)-to-metal (M=W, Mo, and Nb), ligand-to-metal charge transfer (O→M l.m.c.t.) bands of the polyoxometallomanganates such as K 6 Na 2 [MnW 6 O 24 ].12H 2 O (1), K 6 [MnMo 9 O 32 ].6H 2 O (2), and Na 12 [Mn(Nb 6 O 19 ) 2 ]. 50H 2 0 (3) leads to an intramolecular energy transfer from D-M l.m.c.t. triplet states into Mn 4+ , followed by the luminescence of the 2 E→ 4 A 2 transition. Quantum yield of the Mn 4+ luminescence is discussed in terms of both hydrogen bonding at the MnO 6 octahedron and the disparity of the electronic configurations between the excited and ground states for the ligands of condensed MO 6 octahedra. The thermal quenching temperatures of the Mn 4+ luminescence for complexes 1, 2, and 3 were around 50, 350, and 200 K, respectively, which are associated with the potential expansion due to the hydrogen bonding beyond the first coordination sphere of the central MnO 6 octahedron in the anion.

Antiviral Activity of a Keggin Polyoxotungstate PM-19 against Herpes Simplex Virus in Mice

The in vivo activity of the Keggin polyoxotungstate PM-19 [K7(PTi2W10O40)·6H2O] was investigated against herpes simplex virus type 2 (HSV-2) in ddY mice. A single dose of PM-19 at 100mg kg−1administered intraperitoneally (i.p.) immediately after i.p. infection of ddY mice with HSV-2 offered 92% protection against an otherwise lethal HSV-2 infection. PM-19 was less or not effective if given by any route other than the i.p. route. When repeated doses of PM-19 were administered i.p. on day 0 (immediately after infection) and day 1 and 2 after infection, it proved protective over a dosage range of 0.1-50 mg kg−1day−1, its ED50 (50% effective dose, based on the number of survivors) being 0.25 mg kg−1day−1. Under these conditions, ACV was not effective even at doses up to 100 mg kg−1day−1.

Quantitation of herpes simplex viral DNA in Vero cells for evaluation of an antiviral agent using the polymerase chain reaction.

A method for quantitation of the DNA of Herpes simplex virus type 2 (HSV-2)-infected Vero cells by the polymerase chain reaction (PCR) was developed. This method allowed recognition of several molecules of viral DNA among the total DNA extracted from cells. The method could be applied to a very large range (10(-0)-10(-7)) of initial amounts of template. Products of PCR were collected after each cycle for kinetic analysis. Products were subjected to electrophoresis and amplified bands were stained with ethidium bromide. The intensity of fluorescence of each band was measured with a charge-coupled device (CCD) image analyzer. The time course of increases in the relative yield of viral DNA was determined. Two-fold amplification of viral DNA occurred each 6-h cycle from 7 h after infection. Using this method, the yields of viral DNA after treatment with the drug acyclovir (ACV) at 0.1 and 2 microg/ml were about 1/10 and 1/80 of those from nontreated infected cells, respectively. These results indicate that this method makes clear the inhibitory effect of ACV on the synthesis of viral DNA.

Crystal structure of neodymium(III)-diethylene glycol complex

Abstract The title complex was crystallized from a diethylene glycol (DEG) solution containing 0.2 M neodymium trichloride hexahydrate. The X-ray structural analysis of the complex showed that [Nd(DEG)3]3+ cation consists of a central neodymium atom coordinated with nine oxygen atoms from the three DEG ligands with the approximate tricapped-trigonal prismatic configuration. There was a slight difference in conformation among the three DEG chains: one DEG ligand exhibited a zig-zag chain, while the other two were approximately planar due to disordering of the zig-zag conformations. The unequivalence of the conformation among the DEG ligands could be explained by an asymmetric arrangement of Cl− anions surrounding the [Nd(DEG)3]3+ cation.

Electroluminescence Cell Based on Polyoxometalates Pulsed Electric Field‐Induced Luminescence of Decatungstoeuropate Dispersion Layers

electroluminescence (EL) cells have been fabricated with the layer with 40–80 μm thickness, as the emissive medium. The spectral distribution of EL, induced by the applied negative voltage pulse, indicates the presence of three emission envelopes of nitrogen plasma, oxygen‐to‐tungsten (O → W) ligand‐to‐metal charge transfer (LMCT) emission, and Eu3+ f‐f emission for every dispersion layer of Ca2+, Sr2+, or Ba2+ salt of and pellet. The Eu3+ EL lines are similar to Eu3+ photoluminescence lines but with relatively higher intensity in the transition. Typical operating conditions are at 100–300 Hz. A high porosity of the layer which allows a voltage drop to occur in the layer, resulted in a significant contribution of the nitrogen plasma to the total emission. Comparison of transient behaviors among three emissions exhibits an accumulation of charges inside the layer which induces an internal field. Such charges once trapped are released and accelerated by external field or by internal field after the applied pulse is turned off, until enough kinetic energy is acquired to excite . The insulating Mylar film is important for the EL in that it allows accumulation charges to remain inside the layer. The EL intensity is still very low, due to the small number of internal carriers and the small amount of carrier accumulation in the vicinity of the .

Photoluminescent Samarium Octamolybdate

The structure of bis(hexaaquasamarium) octamolybdate hexahydrate, Sm 2 (H 2 O)H 2 [Mo 8 O 27 ].6H 2 O, consists of [(Mo 8 O 27 ) 6− ]∞ chains supported by hydrated Sm 3+ cations. Sm 3+ has tricapped trigonal prismatic coordination with Sm-O distances of 2.38-2.66 A. Mo-O distances in the octamolybdate unit are 1.68-2.49 A

Tetrakis(isopropylammonium) β‐octamolybdate(VI)

The structural analysis revealed that the title compound, 4[C 3 H 10 N][Mo 8 O 26 ], contains discrete centrosymmetric polyanions, β-[Mo 8 O 26 ] 4- , linked to isopropylammonium cations through hydrogen bonds. Some of these hydrogen bonds play an important role in the UV-induced photochromism of this compound