Influence of alkali-treatment temperature on the one-dimensional structure of nanosized TiO2

One-dimensional titania nanomaterials were synthesized by soft chemical processes in an alkali medium. The effect of alkali-treatment temperature on the morphology, porosity, and crystalline phase of TiO₂ nanomaterials was investigated. Nanotubes having an opening end were observed when aging the sample at 130 °C, while conducting the process at 180 °C resulted in nanoribbons with a high aspect ratio. Post-treatment at 300 °C led to the partial transformation from tubular structures into nanoparticles or ribbons into nanobelts. While the monoclinic sodium hexatitanate and anatase crystal had a tubular structure, nanoribbons and nanobelt TiO₂ also showed the presence of hydrogen titanate and sodium trititanate. High surface areas were achieved in as-prepared nanotubes and nanoribbons, 456.5 and 72.1 m²/g, respectively, and a drastic reduction was obtained upon post-treatment at 300 °C to 72.1 and 19.2 m²/g, respectively.     

An investigation of the microstructure,optical and electrical properties of ZITO thin film using the sol–gel method

The multi-compound ZITO transparent conductive oxide (TCO) thin films were synthesized using the sol–gel method. The ZITO thin films with various volume ratios of ZnO to ITO (1:1, 2:1 and 9:1) were crystallized at different temperatures (600–700 °C). The results showed that the crystalline characteristics and optical transmittance were mainly dependent on ITO content and crystallization. Notably, the 650 °C Z₉ITO film not only had better conductivity but also possessed excellent optical transmittance. In addition, the surface roughness of the ZITO films and optoelectric properties of IZO (indium doped ZnO) films were analyzed to confirm the contribution of indium dopants on the optical transmittance. Also, the ZITO films were subjected to the effects of indium and tin dopants and this improved the related characteristics of ZnO films.     

Efficient Olefin Epoxidation by Robust Re4 Cluster‐Supported MnIII Complexes with Peracids: Evidence of Simultaneous Operation of Multiple Active Oxidant Species,MnVO,MnIVO,and MnIII?OOC(O)R

Two new tetranuclear chalcocyanide cluster complexes, [{Mn(saloph)H₂O}₄Re₄Q₄(CN)₁₂]?4 CH₃OH? 8 H₂O (saloph=N,N′‐o‐phenylenebis(salicylidenaminato), Q=Se ( 1 ‐Se), Te ( 2 ‐Te)), have been synthesized by the diffusion of a methanolic solution of [PPh₄]₄[Re₄Q₄(CN)₁₂] into a methanolic solution of [Mn(saloph)]⁺. The structure of 2 ‐Te has been determined by X‐ray crystallography. These rhenium cluster‐supported [Mn^III(saloph)] complexes have been found to efficiently catalyze a wide range of olefin epoxidations under mild experimental conditions in the presence of meta‐chloroperbenzoic acid (mCPBA). Olefin epoxidation by these catalysts is proposed to involve the multiple active oxidants Mn^V?O, Mn^IV?O, and Mn^III? OOC(O)R. Evidence in support of this interpretation has been derived from reactivity and Hammett studies, H₂¹⁸O‐exchange experiments, and the use of peroxyphenylacetic acid as a mechanistic probe. Moreover, it has been observed that the participation of Mn^V?O, Mn^IV?O, and Mn^III? OOC(O)R can be controlled by changing the substrate concentration. This mechanism provides the greatest congruity with related oxidation reactions that employ certain Mn complexes as catalysts.     

Water-soluble aminocalix[4]arene receptors with hydrophobic and hydrophilic mouths

We report the new water-soluble aminocalix[4]arene hosts 1 and 2 with deep hydrophobic cavity facilitating hydrophobic mouth and hydrophilic mouth, respectively. The ¹H NMR titrations revealed that host 1 shows high selectivity for neutral guests 9 and 10, with log K of 4.2 and 4.6, respectively. The host 2 shows log K of 4.9 for binding with guest 15. Moreover, the binding ability of the host 2 for guest 14 is stronger by a factor of 1000 than that of the host 1.     

Tandem one-pot synthesis of α-(aminomethylene)-γ-butyrolactones via regioselective epoxide ring-opening with the Blaise reaction intermediate

A novel tandem one-pot method for the synthesis of α-aminomethylene-γ-butyrolactone derivatives has been developed through the regioselective epoxide opening reactions with the Blaise reaction intermediates, generated by the reaction of a Reformatsky reagent with nitriles. Formation of a modified Blaise reaction intermediate by the addition of a stoichiometric amount of n-BuLi followed by slow addition of epoxide is required for the good yield of γ-butyrolactones.     

New fluorescent and colorimetric chemosensors based on the rhodamine and boronic acid groups for the detection of Hg

Novel rhodamine B (RB) derivatives bearing mono and bis-boronic acid groups were investigated as Hg²⁺ selective fluorescent and colorimetric sensors. These derivatives are first examples of reversible fluorescent chemosensors for Hg²⁺ which utilized boronic acid groups as binding sites. Two new RB-boronic acid derivatives displayed selective ‘Off-On’-type fluorescent enhancements and distinct color changes with Hg²⁺. Selective fluorescent enhancement of two rhodamine derivatives was attributed to ring opening from the spirolactam (nonfluorescent) to ring-opened amide (fluorescent).     

Photoelectron imaging of tetrahydrofuran cluster anions (THF)(n) (-) (1≤n≤100)

Anionic tetrahydrofuran clusters (THF)(n) (-) (1≤n≤100) are studied with photoelectron imaging as gas-phase precursors for electrons solvated in THF. Photoelectron spectra of clusters up to n=5 show two peaks, one of which is attributed to a solvated open chain radical anion and the other to the closed THF ring. At n=6, the spectra change shape abruptly, which become more characteristic of (THF)(n) (-) clusters containing solvated electrons. From n=6-100, the vertical detachment energies (VDEs) of these solvated electron clusters increase from 1.96 to 2.71 eV, scaling linearly with n(-1/3). For fully deuterated (THF-d8)(n) (-) clusters, the apparent transition to a solvated electron cluster is delayed to n=11. Extrapolation of the VDEs to infinite cluster size yields a value of 3.10 eV for the bulk photoelectric threshold. The relatively large VDEs at onset and small stabilization with increasing cluster size compared to other solvated electron clusters may reflect the tendency of the bulk solvent to form preexisting voids that can readily solvate a free electron.