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Zinc oxide (ZnO) films with thicknesses from (9.1 ± 0.7) to (145 ± 7) nm were deposited on silicon substrates by ion-assisted electron beam evaporation (EBE), and transformed to a highly (110)-oriented non-polar phase through thermal treatment at temperatures of 300, 500, and 700 °C. The structural, morphological and optical properties of the ZnO thin films were systematically characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), spectroscopic ellipsometry (SE), and photoluminescence (PL). The XRD and AFM results illustrate that the deposited ZnO films evolved from an X-ray amorphous structure to the polycrystalline hexagonal wurtzite structure with increasing thickness and experienced a crystallographic plane improvement from (102) to the (110) non-polar phase during annealing. The dielectric functions of the whole layer are mainly affected by the dielectric responses near the surface of ZnO nanocrystals and show an upward trend with nanocrystal growth, induced by thickness and annealing temperature. The optical band gaps were also investigated and correlated with the structural properties. In the PL spectra, a strong ultraviolet luminescence (UVL) band and a weak visible green luminescence (GL) band were observed. The intensity ratio of UVL and GL—associated with crystal quality—agrees with the results acquired from other measurements. The two determinants for highly (110)-oriented non-polar ZnO films are the suppression of growth in the (002) direction by ion bombardment and the promotion of the (110) plane induced by diffusion energy during annealing. [ABSTRACT FROM AUTHOR]

Abstract: A novel sulfonamide catalyst based on a room temperature ionic liquid (RTIL) has been developed for the enantioselective reduction of ketones in refluxing toluene. The optically active secondary alcohol products were obtained in good enantiomeric excess and excellent yields. The imidazolium-tagged sulfonamide catalyst can be readily recovered and reused four times without any significant loss of catalytic activity. [Copyright &y& Elsevier]

Optical properties of bismuth (Bi) film in function of temperature have been investigated by spectroscopic ellipsometry (SE). The solid-liquid phase transition point of Bi thin film is found to be ∼262 °C, lower than that of bulk Bi (271.3 °C). The interband transitions of solid Bi occur at 1.82, 3.02 and 4.00 eV, respectively, obtained from imaginary part of dielectric functions and absorption coefficient, which are also consistent with the fitting ellipsometric parameters of the oscillator center energies. A conspicuous difference of optical properties is revealed between solid and liquid Bi, whose characters are semimetal-like and metal-like, respectively. The free electron density of liquid Bi is 10 4 times higher than that of solid Bi. The optical properties of liquid Bi film are mainly influenced by free electrons instead of bound ones. However, with the temperature rising, the increase of both direct and indirect band gaps accords with the characteristics of semiconductor, which can be ascribed to the topological properties of Bi film. This work shows the unique advantage of SE on characterizing the optical properties of topological insulators. [ABSTRACT FROM AUTHOR]

• Spirocyclization via dearomatization of tryptamine derivatives. • Three-component tandem reaction to form C C and C N bond formation. • Easily handled and broadly available formic acid as C1 feedstock. • Commercially available and cost effective organocatalyst. A reductive spirocyclization of tryptamine derivatives with formic acid as a C1 building block has been achieved via dearomatization. The reaction was catalyzed by a commercially available and cost-effective organic base, tetramethylguanidine (TMG). A variety of spiroindolenines were obtained in high yields under mild conditions. [ABSTRACT FROM AUTHOR]

Abstract: A novel arylnitration of alkenes by nitration and C–H functionalization cascade process has been developed. This methodology provides an efficient way to construct a variety of nitro-containing oxindoles and dihydroquinolin-2(1H)-ones. In addition, the process exhibits significant functional group tolerance. Moreover, the use of inexpensive and readily available starting materials makes this practical and atom-economical approach particularly attractive. [Copyright &y& Elsevier]

Abstract: A novel metal-free oxidative arylphosphination of activated N-substituted-N-arylacrylamide derivatives by phosphorylation and C–H functionalization cascade process has been developed. This methodology provides an efficient way to construct a variety of phosphorus-containing oxindole moieties. [Copyright &y& Elsevier]

Abstract: A new method for the synthesis of tricyclic 2,3-dihydro-4-quinolones by the NiCl2(PMe3)2-catalyzed carboamination of alkenes by intermolecular decarboxylative cycloaddition reaction is reported here. Isatoic anhydrides were reacted with various norbornenes to afford the novel structure of quinolones. This protocol is simple and easy to handle. [Copyright &y& Elsevier]

Abstract: A new protocol for the synthesis of polysubstituted isocoumarins from 2-iodobenzoic acid and β-diketone compounds has been developed. The occurrence of C-arylation cyclization reaction in transition-metal-free systems and ortho-induced substrates has been exploited. Reactions using these inexpensive conditions have displayed high functional group tolerance and excellent yields. [Copyright &y& Elsevier]

Abstract: By using Tf2O as a catalyst, we have developed a protocol for the preparation of various dibenzo[a,d]cycloheptene cores via Friedel–Crafts alkylation. Using this method as the key step, we also present concise and useful routes to synthesize the natural products Diptoindonesin D, Pauciflorial F, and (±)-Ampelopsin B. Notably, this process exhibited following very attractive features: (i) the process is metal free, with only catalytic amounts of Tf2O being employed, and (ii) the process is simple and environmentally conscious, avoiding the use of excess amounts of base, oxidant, or other additives. [Copyright &y& Elsevier]