Reactions of AuCl(tht) (tht = tetrahydrothiophene) with various ylides in equimolar amounts give the complexes [AuCl(ylide)]X n (n = 0, ylide = C(PPh3)2 (1a), 4-MeC6H4SO2CHPPh3 (1b); n = 1, X = TfO, ylide = [HC(PPh3)2]+ (2)) and [(AuCl)2{μ-C(PPh3)2}] (3) when using a 2:1 molar ratio. The complex 1a reacts (i) with Tl(acac) to give [Au(acac){C(PPh3)2}] (4) and (ii) with terminal alkynes (with or without added Et3N) to give [HC(PPh3)2][Au(C⋮CC6H4R-4)Cl] (R = H (5a), CN (5b), OMe (5c), NO2 (5d)) instead of the desired complexes [Au(C⋮CC6H4R-4){C{PPh3}2}]. These complexes (R = H (6a), CN (6b), OMe (6c), NO2 (6d), C⋮CPh (6e)) were prepared by the reaction of [Au(acac){C(PPh3)2}] (4) with a large excess of alkynes (ca. 1:25−30). Complex 1b reacts with terminal alkynes in the presence of Et3N differently from 1a, giving the complexes [Au(C⋮CC6H4R-4){CH(PPh3){S(O)2C6H4Me-4}}] (R = H (7a), NC (7b), OMe (7c), NO2 (7d), C⋮CPh (7e)). The reaction of PPN[Au(acac)2] with the phosphonium salt [H2C(PPh3)2](TfO)2 or [4-MeC6H4S(O)2CH2PPh3]TfO in 1:2 stoichiometry afforded the cationic complex [Au(ylide)2](TfO) n , where the ylide is [HC(PPh3)2]+ (n = 3, 8a) or 4-MeC6H4S(O)2CHPPh3 (n = 1, 8b), respectively. The crystal structures of [4-MeC6H4S(O)2CH2PPh3]TfO, 1b·0.5CH2Cl2, 3·3CH2Cl2, 5a, 5c, 6d·THF, and 8b have been determined.

We report here two different simple, one‐pot, and low cost chemical synthetic routes for the preparation of Cu2O nanocrystals: (a) thermal decomposition of copper–organic precursors copper(II) acetate or copper(II) acetylacetonate in long chain organic solvents oleyl alcohol and trioctylamine, respectively, at 170 °C and (b) a surfactant‐free solvothermal approach involving the reaction of copper(II) acetylacetonate in acetone at 140 °C. The structure and morphology of the nanocrystals have been characterized in detail by XRD, FTIR spectroscopy, Raman spectroscopy, and high‐resolution transmission electron microscopy (HRTEM). The optical properties of the nanocrystals have been explored by diffuse‐reflectance spectroscopy (DRS) and a blueshift of the optical band gap of the nanocrystals is observed owing to size effects. Based on the FTIR, GC–MS, and 13C{1H} NMR studies of post‐reaction solutions, different formation mechanisms for the Cu2O nanocrystals, which depend on the synthetic approach, have been proposed. Oleyl alcohol and trioctylamine play dual roles as solvents and mild reductants and reduce CuII species to CuI species during the course of the thermal decomposition reactions. The solvothermal reaction of copper(II) acetylacetonate in acetone possibly proceeds by acetylacetone‐mediated reduction of Cu2+ to Cu+ in the absence of any reducing agent. The potential of Cu2O nanocrystals as photocatalytic materials for hydrogen generation from water/methanol (2:1) mixtures under UV/Vis irradiation has also been evaluated. The results show that all the nanocystalline Cu2O samples generate H2.

We report the preparation, characterization, and magnetic properties of highly crystalline colloidal Fe-doped indium oxide nanoparticles. The nanoparticles have been prepared in high yields by simple one-pot thermal decomposition of indium and iron precursors in hexadecylamine and can be easily dispersed in solvents like chloroform and toluene. Detailed X-ray diffraction, microstructure, and Raman studies reveal that the nanoparticles are single phase cubic bixbyite structure without any parasitic secondary phases. DC magnetization studies as a function of temperature and field indicate that nanoparticles are weakly ferromagnetic at room temperature (RT). This observation is further confirmed by the electron paramagnetic resonance spectra of the samples, which show a distinct ferromagnetic resonance signal at RT.

The effect of pressure on the vibrational properties of bulk and nanocrystalline powders of cubic bixbyite-type In2O3 has been investigated at room temperature by means of Raman spectroscopy up to 31.6 and 30 GPa, respectively. We have been able to follow the pressure dependence of up to sixteen and seven Raman modes in bulk and nanocrystalline cubic In2O3, respectively. The experimental frequencies and pressure coefficients of the Raman-active modes of bulk cubic In2O3 at ambient pressure are in good agreement with those predicted by our theoretical ab initio calculations. Furthermore, a comparison of our experimental data with our calculations for the Raman modes in rhombohedral corundum and orthorhombic Rh2O3-II structures and with already reported Raman modes of rhombohedral corundum-type In2O3 at room pressure indicate that Raman scattering measurements provide no experimental evidence of the cubic to rhombohedral or cubic to orthorhombic phase transitions either in bulk material or in nanocrystals up to 30 GPa.

No abstract

Self supporting poly(methyl methacrylate) (PMMA)/In 2 O 3 with varying In 2 O 3 content (1, 2, 5 and 10 wt% In 2 O 3 loading) nanocomposite films have been prepared by solvent-casting and spin casting techniques.The nanocomposite films have been structurally characterized by X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy and the results confirm the incorporation of In 2 O 3 nanoparticles in the PMMA matrix. The thermal properties of the nanocomposite films have been investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results show that the degradation of the polymer occurs at higher temperature in the presence of In 2 O 3 nanoparticles and even a small amount of In 2 O 3 nanoparticles ($1 wt%) can greatly improve the thermal stability of PMMA. The UV-visible spectra of the nanocomposite films show that the films are UV-absorbing, and highly transparent in the visible region.

No abstract

The preparation, characterization, and magnetic properties of dispersible Co-and Ni-doped ZnO nanocrystals (NC) are reported. The nanocrystals, Zn 1-x TM x O where x ) 0-0.07 for TM ) Co and x ) 0.02, 0.03 for TM ) Ni have been synthesized by nonhydrolytic alcoholysis esterification elimination reaction using anhydrous metal carboxylates as precursors in the presence of oleic acid and oleyl alcohol at temperatures as low as 220°C. The prepared nanocrystals can be easily dispersed in solvents like chloroform and toluene. Detailed X-ray diffraction (XRD) using synchrotron radiation (SR), microstructure, and Raman studies reveal that the Codoped ZnO nanocrystals are single-phase wurtzite structure without any parasitic secondary phases and Co atoms are incorporated into the ZnO lattice and located at the substitutional sites of the Zn atoms. Magnetic studies as a function of temperature and field indicate that Co-and Ni-doped zinc oxide nanocrystals are ferromagnetic at room temperature (RT). The observed ferromagnetism in Co-doped ZnO nanocrystals is interpreted in terms of a spin-split donor impurity-band model. The detection of donor defects bound to Co sites by Raman spectroscopy and decreased magnetization in oxygen-annealed samples suggest that activation of ferromagnetism depends on defects, such as oxygen vacancies (V O ) and zinc interstitials (Zn i ). On the other hand, the observation of secondary phases like NiO and Ni in the powder XRD patterns of Ni-doped ZnO nanocrystals suggests the extrinsic origin of ferromagnetism in this material.