Charge ordering and carrier generation by air oxidation of a nickel complex with selenium-containing extended-tetrathiafulvalenedithiolate ligands

The structures and electrical properties of ((n)Bu(4)N)[Ni(dmstfdt)(2)] (1), ((n)Bu(4)N)(2)[Ni(dmstfdt)(2)] (2), and ((n)Bu(4)N)(3)[Ni(dmstfdt)(2)](2) (3), where dmstfdt = extended-tetrathiafulvalenedithiolate ligand, were examined. The fresh crystal of 1 was found to be a Mott insulator, but the crystal gradually became highly conducting because of air oxidation. Compound 3 exhibited a semiconducting charge-ordering state.     

Synthesis and properties of unsymmetrically extended π-electronic conjugation system of octaethylporphyrin(Ni)-dihexybithiophene-octaethylporphyrin(Pd) connected with diacetylene linkage

Orientational isomers of the diacetylene-group connected dihexybithiophene (DHBTh) derivatives have been synthesized, in which the different octaethylporphyrin (OEP(M); M=Ni or Pd) rings are attached at the ends. Reflecting the unsymmetrical structural feature, the peculiar electronic properties of the extended OEP(Ni)-DHBTh-OEP(Pd) system were observed.     

Spectrophotometric determination of formation constants of various types of complexes by use of another competing ligand

A method has been developed for determining the formation constants of various colored complexes, ML and ML₂, and their protonated forms, spectrophotometrically, by measuring the absorbance of all forms of the colored complexes in the absence and presence of another ligand, Y, which forms the colorless complex MY, with a known formation constant. This method is based on the competition between the two ligands, L and Y, for the metal ion. An experimental test has been done for the Zn(II)-4-(2-pyridylazo)resorcinol (PAR) (H₂L) system by using nitrilotriacetic acid (NTA) as another ligand, Y. The results showed that the concentrations of PAR used were suitable for the study of 1:2 complexes, ZnL₂, ZnL(HL) and Zn(HL)₂, but were too high to study the 1:1 complexes. With the aid of the formation constants of ZnL and ZnHL determined previously, the experimental data gave an approximate value for the formation constant of ZnY (Y = NTA) which agreed with the published value.     

3]rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure

A novel [3]rotaxane composed of two 25-membered crownophanes and one axle molecule having two anthryl end groups was successfully synthesized via covalent bond formation followed by aminolysis, and can incorporate caesium ion into the space between the two macrocycles as a 1 : 1 sandwich-type complex, whereas it makes a 1 : 2 complex with lithium ion.     

Enantioselective cyclopropanation reaction using a conformationally fixed pyridinium ylide through a cation-π interaction

Using a chiral pyridinium ylide with a fixed conformation through a cation-π interaction performs enantioselective cyclopropanation of electron-deficient olefins. ¹H NMR, X-ray structural analysis and DFT calculations elucidated the self-complexation and the face-to-face arrangement between the pyridinium and the phenyl rings. The absolute configuration of the product was determined after conversion into a bicyclic cyclopropane derivative.     

Magnetic transitions of single-component molecular metal [Au(tmdt)2] and its alloy systems

A single-component molecular conductor [Au(tmdt)2] (tmdt = trimethylenetetrathiafulvalenedithiolate) undergoes an antiferromagnetic phase transition at unprecedentedly high temperature (TN = 110 K). Black microcrystals of alloys, [Ni1-xAux(tmdt)2] (0.0 < x < 1.0) were prepared. The Au-rich system exhibited an antiferromagnetic transition. Metallic single crystal was obtained for x = 0.25.     

Toxicity of Methanol and Formaldehyde Towards <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> as Assessed by DNA Microarray Analysis

To assess the toxicity of the C1 compounds methanol and formaldehyde, gene expression profiles of treated baker’s yeast were analyzed using DNA microarrays. Among approximately 6,000 open reading frames (ORFs), 314 were repressed and 375 were induced in response to methanol. The gene process category “energy” comprised the greatest number of induced genes while “protein synthesis” comprised the greatest number of repressed genes. Products of genes induced by methanol were mainly integral membrane proteins or were localized to the plasma membrane. A total of 622 and 610 ORFs were induced or repressed by formaldehyde, respectively. More than one-third of the genes found to be strongly repressed by formaldehyde belonged to the “protein synthesis” functional category. Conversely, genes in the subcategory of “nitrogen, sulfur, and selenium metabolism” within “metabolism” and in the category of “cell rescue, defense, and virulence” were up-regulated by exposure to formaldehyde. Our data suggest that membrane structure is a major target of methanol toxicity, while proteins were major targets of formaldehyde toxicity.     

Global dynamics of a discretized SIRS epidemic model with time delay

We derive a discretized SIRS epidemic model with time delay by applying a nonstandard finite difference scheme. Sufficient conditions for the global dynamics of the solution are obtained by improvements in discretization and applying proofs for continuous epidemic models. These conditions for our discretized model are the same as for the original continuous model.