Anhydrobiisatic acid 6:12-Oxa-5:6:11:12-tetrahydrophenhomazine-6:12-dicarboxylic acid

Anhydrobiisatic acid (IVa), a new type of compound containing the phenhomazine ring system, has been obtained by self-condensation of isatic acid—(o-aminophenyl)glyoxylic acid—. The structure of this acid has been established and derivatives have been prepared. N:N′-Dimethylanhydrobiisatic acid (IVc) has been resolved into optically active components.     

Acetalation studies-III: synthesis of 1,2:3,4:5,6-tri-O-isopropylidene-galactitol

Treatment of galactitol uith 2,2-dimethoxypropane in dimethylsulphoxide unexpeatedly yields the title triketal, containing a cis-dioxolane ring; the structure of the product has been confirmed by spectral measurements.     

The mass spectrum of 1:12, 2:3, 4:5, 6:7, 8:9, 10:11-hexabenzocoronene

The mass-spectra of 1:12, 2:3, 4:5, 6:7, 8:9, 10:11-hexabenzocoronene and the isomer 1:2, 3:4, 5:6, 7:8, 9:10, 11:12-hexabenzocoronene have been examined. The former is typically that of an aromatic conjugated hydrocarbon and is sparse, the latter is more intense. It is conjectured that the former may be found in interstellar space.     

Light-emitting properties of amorphous Si:C:O:H layers fabricated by oxidation of carbon-rich a-Si:C:H films

Amorphous hydrogenated carbon-rich silicon–carbon alloy film (a-Si_0.3C_0.7:H) was deposited by reactive dc-magnetron sputtering of silicon target in argon–methane gas mixture. As-deposited film exhibits white photoluminescence at room temperature. After the deposition the samples were thermally annealed in dry Ar, wet Ar, or dry O₂ flow at 450 °C for 30 minutes that resulted in the enhancement of the photoluminescence intensity by a factor of about 5, 8 and 12 respectively. Spectral distribution of light emission was almost unchanged at the annealing in dry and wet argon while the oxidation in pure oxygen resulted in strong enhancement of a “blue” shoulder in the spectrum. EPR measurements at room temperature showed the decrease of spin concentration after thermal treatment in dry and wet argon and no EPR signal was detected after annealing in oxygen. FTIR and XPS measurements evidenced the formation of a-Si:O:C:H composite material after dry oxidation. Based on the measurements of photoluminescence in the temperature range 7–300 K it is suggested that light-emitting efficiency of a-Si_0.3C_0.7:H is determined by migration of the photo-excited carriers to non-radiative recombination centers. The physical mechanisms that can be involved in the strong enhancement of visible photoluminescence in Si:C:O:H layers are discussed.     

The structure of a trimolecular liquid: tert-butyl alcohol:cyclohexene:water

The structure of the trimolecular liquid mixture of 2:6:1 cyclohexene, tert-butyl alcohol, and water has been investigated using hydrogen/deuterium substitution neutron scattering techniques, and a three-dimensional structural model refined to be consistent with the experimental data has been built using the technique of Empirical Potential Structure Refinement. The model shows a well-mixed solution of the three molecular components where the competing interactions between the nonpolar cyclohexene and polar water molecules are balanced in the solution leading to largely pure-alcohol-like interactions between the tert-butyl alcohol molecules. Cyclohexene molecules favor direct solvation by alcohol methyl groups while water molecules are accommodated, dispersed throughout the solution, via hydrogen bonding interactions with the alcohol molecule hydroxyl groups. Rare occurrences of direct cyclohexene-water interactions are of the classic hydrophobic hydration type and no evidence is found for microscopic heterogeneity in the trimolecular mixture in contrast to the general findings for binary alcohol-water solutions.     

Yb:Er:Tm:LiTaO3的上转换发白光性能研究

980 nm脉冲激光激发下,首次通过高温固相法制备Yb(10%):Er(1%):Tm(1%):LiTaO3(摩尔分数)多晶粉并实现室温上转换白光.X射线粉末衍射测试结果表明,Yb:Er:Tm:LiTaO3中的掺杂离子并没有改变晶格结构,以取代的方式存在于钽酸锂晶格中.结合功率曲线测试结果和上转换机制研究发现,产生上转换蓝光的Tm3+离子1G4态的布居主要来自双光子同时吸收过程.而单光子上转换输出的红光,则由Tm3+和Er3+离子之间的交叉弛豫过程产生,即3F2/3(Tm3+)+4I15/2(Er3+)→3H6(Tm3+)+4I9/2(Er3+).上转换绿光来源于Yb/Er离子对的二次能量传递.     

Holographic Storage Properties of In：Fe：Mn：LiNbO3 Crystals

In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0,1,2,3 mol%) in the melts,while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%,respectively. The location of doping ions was analyzed by Ultraviolet-visible absorption spectra and differential thermal analysis. The diffraction efficiency (η),writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt,the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift,the Curie temperature of crystal increases firstly and then decreases,the storage ratio speeds up,diffraction efficiency decreases,and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe: Mn:LN crystal with different doping concentration of In3+ was investigated,suggesting the In: Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals.     

High-throughput screening assay for the quantification of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 in HepG2 cells using RapidFire mass spectrometry

Ceramides are known to be involved in various biological processes with their physiological levels elevated in various disease conditions such as diabetes, Alzheimer's, atherosclerosis. To facilitate the rapid screening of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 inhibition in HepG2 cells, a RapidFire coupled to tandem mass spectrometry (RF–MS/MS) method has been developed. The RF platform provides an automated solid-phase extraction system that gave a throughput of 12.6 s per sample to an MS/MS system using electrospray ionization under the positive ion mode. Chromatographic separation of Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, and d18:1/22:0 was achieved using a ternary gradient on C₈ type E cartridge. The MS/MS ion transitions monitored were 538.2 → 264.2, 650.7 → 264.2, 648.6 → 264.2, 566.4 → 264.2, 510.4 → 264.2, 594.4 → 264.2, 622.5 → 264.2, and 552.3 → 250.2 for Cer d18:1/16:0, d18:1/24:0, d18:1/24:1, d18:1/18:0, d18:1/14:0, d18:1/20:0, d18:1/22:0, and the internal standard (Cer d17:1/18:0), respectively. The RF–MS/MS methodology showed an excellent performance with an average Z′ value of 0.5–0.7. This is the first report of an RF–MS/MS assay for screening of ceramides which is amenable for high-throughput screening.     

New helical foldamers: heterogeneous backbones with 1:2 and 2:1 alpha:beta-amino acid residue patterns

Foldamers, oligomers with strong folding propensities, are subjects of growing interest because such compounds offer unique scaffolds for the development of molecular function. We report two new foldamer classes, oligopeptides with regular 1:2 or 2:1 patterns of alpha- and beta-amino acid residues. Two distinct helical conformations are detected via 2D NMR in methanol for each backbone. One of the helices for each backbone is characterized via X-ray crystallography.     

Tri-n-octylphosphine sulfide: : A selective organic extractant

Tri-n-octylphosphine sulfide (TOPS) has been investigated as the stationary phase in reversed-phase partition paper Chromatographie separations using nitric or hydrochloric acids as the mobile phase. TOPS has also been studied as an extractant for metal ions. Silver, mercury (II), and palladium (II) were found to have RF values of zero when nitric acid was used as the mobile phase. These same ions were also selectively extracted from aqueous nitric acid solutions. Gold(III), mercury(II), palladium (II), and platinum (IV) were found to have RF values of zero when hydrochloric acid was used as the mobile phase. However, only gold(III) and mercury(II) were extracted from aqueous hydrochloric acid solutions in liquid-liquid extraction systems. Several separations were successfully performed from 1 M nitric acid.     

Review: Mixed-valent metallodendrimers: design and functions

Various types of mixed-valent metallodendrimers and star-shaped macromolecules containing ferrocenyl, biferrocenyl, or other redox-robust iron groups with rigid or flexible tethers of short and long lengths mostly studied in the authors’ laboratory including the class type in terms of Robin-Day classification and their functions including electrode modification, sensing, and nanoparticle templates are discussed in this mini review.