Hydrogen-bond Networks Involving Protonated Bicapped-Keggin Tetradecavanadophosphate Anions

Tetraphenylphosphonium salts of protonated tetradecavanadophosphate (PV₁₄) anions, [(C₆H₅)₄P]₄H₅PV₁₄O₄₂·5H₂O (1) and [(C₆H₅)₄P]₂H₇PV₁₄O₄₂·6H₂O (2), have been synthesized and their crystal structures have been determined. Compound 1 crystallizes in triclinic, P1 with a=12.7866(1), b=15.5261(2), c=16.0730(3) ?, α=109.358(1), β=98.411(1), γ=110.040(1)°. Synchrotron radiation X-ray diffraction revealed that compound 2 crystallizes in monoclinic, P2₁/c with a=16.821(1), b=25.163(2), c=18.817(1) ?, β=109.992(2)°. In compound 1, the PV₁₄ anions are linked into a one-dimensional chain structure by water molecules of crystallization. In compound 2, hydrogen bonds directly link PV₁₄ anions into a zigzag chain, which are then woven into a three-dimensional network by hydrogen bonds bridged by water molecules.Dedicated to Professor Michael T. Pope on the occasion of his retirement, in recognition of his outstanding contributions to the polyoxometalate chemistry.     

Further studies on palytoxin. I.

The structures of two degradation products of N-(p-bromobenzoyl) palytoxin were elucidated, and then the sequences of those fragments were determined.     

Synthesis and properties of a bridged phenalenone incorported into bicyclo[3.2.2]nonane skeleton. 6,9-dihydro-6,9-ethenocyclohepta[gh]phenalen-1-one

6,9-Dihydro-6,9-ethenocyclohepta[gh]phenalen-1-one ($\text{1}$) has been synthesised starting from the Diels-Alder adduct ($\text{6}$) of acepleiadiene ($\text{5}$) and maleic anhydride through 10 steps with reasonable yields. Spectroscopic properties of $\text{1}$ suggestged the intramolecular electron supply from the remote ethylenes to the phenalenone π-systems in the ground-state of this molecule.     

STATIC QUENCHING OF EXCITED STATE OF TRIS(BIPYRIDINE)RUTHENIUM(II) COMPLEX-CONTAINING POLYMER BY SODIUM ANTHRAQUINONE-2-SULFONATE

Abstract— Quenching of excited state of Ru(bpy)₂(poly-4-methyl-4'-vinyl-2,2'-bipyridine)Cl₂ by sodium anthraquinone-2-sulfonate was found to be a static process. The quenching was interpreted by application of a modified Perrin model. Radius of the quenching sphere was estimated to correspond to 6.65 monomer units and was unchanged on varying the Ru²+ content of the polymer. Energy migration along the polymer chain was denied.     

Kinetic stabilization of the o-quinoidal 3,4-benzotropone system

Kinetic stabilization of the o-quinoidal 3,4-benzotropone system was investigated. The parent 3,4-benzotropone undergoes rapid [pi8 + pi10] dimerization in fluid solution even at -78 degree C while triptycene-fused derivative having a tert-butyl group at the C6 position of the tropone moiety was found to be stable indefinitely under similar conditions. The relative importance of the triptycene moiety and the tert-butyl group in for the kinetic stabilization was evaluated.     

Effect of growth substrates on production of new soluble glucose 3-dehydrogenase in Halomonas (Deleya) sp. α-15

Halomonas (Deleya) sp. α-15 produces new co-factor binding soluble glucose 3-dehydrogenase (G3DH), which oxidizes the third hydroxy group of pyranose. This study investigated the condition of efficient production of G3DH using Halomonas (Deleya) sp. α-15. This enzyme was inducible, and α-methyl-D-glucoside, isopropyl-thioga lactopyranoside (IPTG) and lactose were revealed to be suitable carbon sources for G3DH induction. Maximum G3DH production was achieved by using minimal medium containing 0,8% (w/v) lactose with a productivity of 470U/1.     

A self-assembled nano optical switch and transistor based on a rigid conjugated polymer, thioacetyl-end-functionalized poly(para-phenylene ethynylene)

A nanometer-scale optical switch and transistor were fabricated with thioacetyl-end-functionalized poly(para-phenylene ethynylene)s and Au nanogap electrodes by self-assembly. With photoirradiation, the switch can be switched on/off quickly with a switching ratio as high as 1000. Moreover, the device works well as a p-type transistor. With an increase in gate bias, strong conductance oscillation was observed in this self-assembled transistor (under low temperature 147 K), which is very likely due to single-electron charging oscillations arising from electron tunneling through the nanometer-scale transistor.     

Visible-light-responsive photocatalytic reaction on tetrahedrally-coordinated chromium oxide moieties loaded on ZSM-5 zeolites and HMS mesoporous silica: partial oxidation of propane

Chromium oxide (Cr-oxide) moieties loaded on ZSM-5 zeolites and HMS mesoporous silica molecular sieves were prepared by an impregnation method and characterized by various spectroscopic methods (XRD, XAFS, UV-Vis, photoluminescence) and their photocatalytic reactivities for partial oxidation of propane under visible light irradiation were investigated. The local structure of Cr-oxide species depended to a large extent on the zeolite types and Si/A1 ratios of zeolites. Tetrahedrally-coordinated isolated Cr-oxide moieties can be loaded on HMS and ZSM-5 having the higher Si/A1 ratios. On these catalysts, in the presence of propane and O₂, a partial oxidation proceeded under visible light irradiation to produce acetone with high selectivity. The charge-transfer excited state of the tetrahedral Cr-oxide moieties plays a significant role in the selective photocatalytic reactions under visible light irradiation.     

Stereospecific polymerization of benzyl vinyl ether by BF3·OEt2

Polymerization of benzyl vinyl ether was carried out by BF₃·OEt₂, and the effects of polymerization conditions on the stereoregularity of the polymer were studied by NMR analysis. The polymerization at ?78°C in toluene gave a highly isotactic polymer. The isotacticity of the polymer was independent of the catalyst concentration but increased with a decrease in the initial monomer concentration and decreased slightly on raising the reaction temperature. When the polymerizations were carried out in toluene—nitroethane mixtures, a gradual decrease in the isotacticity and a rapid decrease in the molecular weight of the polymer were observed with increasing nitroethane in the solvent. The molecular weight of the polymer was almost constant, regardless of the catalyst concentration, and increased with increasing initial monomer concentration and decreasing polymerization temperature. When the polymerization was performed in toluene at ?78°C with a small amount of water or benzyl alcohol, a linear relationship was found between the reciprocal DP of the polymer and water or benzylalcohol concentration. The mechanisms of the initiation reaction and the stereoregulation in the polymerization were also discussed.     

Isolation and structure of clithioneine,a new amino acid betaine from clitocybeacromelalga.

A new amino acid betalne clithioneine was isolated from $\text{Clitocybe}$$\text{acromelalga}$. The structure was determined as $\text{1}$ by spectral analyses and chemical degradations.