Supported Gold Nanoparticles for Efficient α‐Oxygenation of Secondary and Tertiary Amines into Amides

Although the α‐oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O₂ as the terminal oxidant have no precedent. This report describes a novel, green α‐oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al₂O₃). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α‐oxygenation utilizes O₂ as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by‐product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α‐oxygenation provides a convenient method for the synthesis of ¹⁸O‐labeled amides using H₂¹⁸O as the oxygen source.     

Iron–Oxalato Framework with One‐Dimensional Open Channels for Electrochemical Sodium‐Ion Intercalation

Discovery of a new class of ion intercalation compounds is highly desirable due to its relevance to various electrochemical devices, such as batteries. Herein, we present a new iron–oxalato open framework, which showed reversible Na⁺ intercalation/extraction. The hydrothermally synthesized K₄Na₂[Fe(C₂O₄)₂]₃ ? 2 H₂O possesses one‐dimensional open channels in the oxalato‐bridged network, providing ion accessibility up to two Na⁺ per the formula unit. The detailed studies on the structural and electronic states revealed that the framework exhibited a solid solution state almost entirely during Na⁺ intercalation/extraction associated with the reversible redox of Fe. The present work demonstrates possibilities of the oxalato frameworks as tunable and robust ion intercalation electrode materials for various device applications.     

Cu_xCo_(1-x)/Al_2O_3/FeCrAl整体式催化剂上甲苯催化燃烧(英文)

以FeCrAl合金薄片为基底,Al2O3浆料为过渡胶体,不同摩尔比的Cu、Co为催化活性组分,制备了一系列CuxCo1-x/Al2O3/FeCrAl(x=0-1)新型整体式催化剂.采用X射线粉末衍射(XRD),扫描电子显微镜(SEM),X光电子能谱(XPS)和程序升温还原(TPR)等手段对催化剂的结构进行了表征.在微型固定床反应器上评价了催化剂的催化甲苯燃烧性能.研究结果表明:在所制备的整体式催化剂上,当Cu含量比较低时,形成了Cu-Co-O固溶体;当Cu含量比较高时,可以测得CuO的衍射峰.催化剂表面颗粒大小和形貌与Cu、Co摩尔比密切相关.在催化剂表面,Co以Co2+和Co3+价态存在,而Cu主要以Cu2+价态存在.催化剂中的Cu可以改善Co的氧化还原性,从而有利于催化剂活性的提高.在所制备的催化剂中,Cu0.5Co0.5/Al2O3/FeCrAl催化剂具有最好的活性,甲苯在374oC可以完全催化燃烧消除.     

Molecule/radical reactions prior to ionization under negative chemical ionization conditions

It is shown that alkyl radical species present in CH₄ or iso-C₄H₁₀ plasma can react with substrate molecules to give [M+C_nH_2n] species. These species become evident especially in negative chemical ionization as [M+C_nH_2n]^?˙ and, less obviously, in positive chemical ionization as [M+C_nH_2n+1]⁺ ions which, for example in natural products chemistry, may be mistaken for a series of homologous compounds present in the sample.     

Control of site selectivity in trifluoromethylation of alkenes bearing a pendant indolyl group: Synthesis of CF3-containing tetrahydrocarbazoles

We present a tetrahydrocarbozole-forming carbo-trifluoromethylation of indoles bearing an alkenyl group at the C3 position. The reaction proceeded selectively with the combination of TsOH·H₂O as a catalyst and CH₂Cl₂ as a solvent. The site-selectivity could be altered by changing the reaction solvent; the use of THF instead of CH₂Cl₂ increased the formation of aromatic trifluoromethylation products.     

Conformational analysis of some dimethylheptanes with the aid of normal coordinate calculations

Infrared spectra were obtained for the series of 2,X-dimethylheptanes (X = 2,3,4,5,6) and were interpreted with the aid of normal coordinate calculations. 2,2-DMH exists as two conformers, with the C_s conformer being the only one present in the crystalline solid. 2,3-DMH exists in at least three conformations, all of C₁ symmetry. Ambiguities in spectral data indicate that more conformations are present. Two C₁ conformations of 2,4-DMH were shown to be present, but an unassigned band may indicate the presence of a third conformer. The presence of at least four conformers, all of C₁ symmetry, was shown to be necessary to explain the spectrum of 2,5-DMH. Finally, 2,6-DMH was shown to exist as three conformers, of symmetries C_s, C₂, and C₁. Vibrational assignments were made for all the probable conformers of all five compounds.     

Development of CeO<Subscript>2</Subscript>- and TiO<Subscript>2</Subscript>-incorporated aluminium metal-composite matrix with high resistance to corrosion and biofouling

Cerium oxide (CeO₂) is a potential corrosion inhibitor for aluminium, and titanium oxide (TiO₂) is an efficient anti-fouling agent in the marine environment. The present study explored the possibility of incorporating CeO₂ and TiO₂ in aluminium to prepare a metal matrix composite that could have high corrosion and biofouling resistance under marine conditions. Such incorporation of CeO₂ and TiO₂ in pure aluminium offered high resistance to corrosion and biogrowth under marine conditions as evidenced during different tests. The specimens exhibited more anodic and stable open circuit potential throughout the period of the study. The optimum concentration of CeO₂ and TiO₂ was found to be 0.2 and 0.1%, respectively. The present results lay emphasis on the potential scope of the use of CeO₂- and TiO₂-incorporated aluminium in marine environments.     

The mass spectra of aluminum isopropoxide

The mass spectra of aluminum isopropoxide show that polymers, [Al(OC₃H₇)₃]_x where x = 1 to 7, can be present in the vapor and are, therefore, probably present in the bulk sample. The polymeric composition of the vapor depends on the previous history of the sample. Exact mass measurements on many of the ions along with data on a number of metastable peaks support the proposed fragmentation mechanisms. Loss of 102 mass units between intense peaks in the mass range above 500 a.m.u. leads to the suggestion that the higher polymers may be used as high mass marking substances.     

Reduction of Pertechnetate by Chemical and Photochemical Approaches and Incorporation of Tc(IV) into Titanium Dioxide

Technetium-99 is a prevalent fission product from nuclear waste. The long half-life (211,000 yr) and environmental mobility of pertechnetate (TcO₄⁻) render Tc particularly challenging to isolate and stabilize. Here we present two approaches for development of potential wasteforms using titanium dioxide, TiO₂. Approach 1 is a low temperature chemical synthesis of TiO₂ doped with Tc(IV) from TcO₄⁻ intended to mimic the Tc waste stream from the UREX family of separations and removes 98.5 % of the Tc, mainly present as edge-shared Tc(IV) pairs. Approach 2 utilizes TiO₂ to photocatalytically reduce TcO₄⁻ to Tc(IV) stabilized on the surface of or within the TiO₂ lattice. The %Tc removed from solution and adsorbed to TiO₂ is pH dependent, with the maximum Tc(IV) adsorbed at pH 3–4 as either TcO₂ or edge-sharing Tc(IV) octahedra. The Tc(IV)-TiO₂ composites materials formed by both approaches are suitable for consolidation into a dense wasteform by Hot Isostatic Pressing (HIPing).     

Imido,amino and amido coordination of diaminouracil to rhenium(V)

Reaction of equimolar quantities of cis-[ReO₂I(PPh₃)₂] with 5,6-diamino-1,3-dimethyl-2,4-dioxopyrimidine (H₂ddd) in acetonitrile led to the formation of [Re(ddd)(Hddd)I(PPh₃)₂] (ReO₄) (1). A single-crystal X-ray crystal structure shows that ddd is coordinated as a monodentate through the doubly deprotonated amino nitrogen and is therefore present as an imide. The chelate Hddd is coordinated as a bidentate via a neutral amino nitrogen atom, trans to the imido nitrogen, and a singly deprotonated amido nitrogen atom, trans to the iodide.     

Biogeochemical behaviour of plutonium and americium and geochemical modelling of the soil solution

Field observations suggest that plutonium and americium in the environment are present in very different chemical forms in the interstitial waters of an intertidal sediment. Themodynamic modelling using the PHREEQE code predicts that plutonium is present entirely in oxidation state (V) as the PuO₂CO ₃ ^– ion, whereas americium is present entirely in oxidation state (III), largely as the uncharged Am(OH)CO₃ species, but with significant concentrations of the Am³⁺ and the AmSO ₄ ⁺ ions. There are, however, differences between these predictions and others published for a very similar system which apparently arise from uncertainties in the thermodynamic data. Field data cannot resolve these differences unambiguously.     

A simple synthesis of symmetric phthalocyanines and their respective perfluoro and transition‐metal complexes

We report a simple synthesis protocol for making phthalocyanines (Pcs) starting from phthalonitriles. This method is general and requires no specialised equipment. The complexes are isolated and characterised using X‐ray diffraction, NMR, FTIR and Raman spectroscopy and high‐resolution mass spectrometry. First, we study and present a one‐step synthesis route to a metal‐free Pc (H₂PcH₁₆), as well as to the corresponding MPcH₁₆ complexes of Mn, Fe, Co, Ni, Cu and Zn. Then, we show that this route can also be used to make the fluorinated Pc analogues (MPcF₁₆). Finally, we present a new and useful procedure for inserting a metal ion into a metal‐free H₂PcH₁₆ ring, by direct metalation, yielding the corresponding MPcH₁₆ complex. This last method is especially useful if you want to make different MPcH₁₆ complexes.     

Preparation of Bioactive PDMS-Modified CaO–SiO2–TiO2 Hybrids by the Sol-Gel Method

Much attention has been focused on the development of a new type of bioactive material with mechanical properties analogous to those of natural bone. The present authors previously showed that some polydimethylsiloxane (PDMS)-modified CaO–SiO₂–TiO₂ hybrids prepared by sol-gel method show apatite-forming ability in a simulated body fluid (SBF), which is indicative of bioactivity. In the present study, effects of composition of PDMS-modified CaO–SiO₂–TiO₂ hybrids on their bioactivity and mechanical properties were investigated. The bioactivity of the hybrids increased with decreasing PDMS content and increasing TiO₂ content. Their strain at failure increased with increasing PDMS content and decreasing TiO₂ content. Some samples showed high bioactivity, as well as analogous mechanical properties to those of human cancellous bones. This type of hybrids might be useful as a bone-repairing material.     

Alkyltin Keggin Clusters Templated by Sodium

Dodecameric (Sn₁₂) and hexameric topologies dominate monoalkyltin–oxo cluster chemistry. Their condensation, triggered by radiation exposure, recently produced unprecedented patterning performance in EUV lithography. A new cluster topology was crystallized from industrial n ‐BuSnOOH, and additional characterization techniques indicate other clusters are present. Single‐crystal X‐ray analysis reveals a β‐Keggin cluster, which is known but less common than other Keggin isomers in polyoxometalate and polyoxocation chemistry. The structure is formulated [NaO₄(BuSn)₁₂(OH)₃(O)₉(OCH₃)₁₂(Sn(H₂O)₂)] (β‐NaSn₁₃). SAXS, NMR, and ESI MS differentiate β‐NaSn₁₃, Sn₁₂, and other clusters present in crude “n ‐BuSnOOH” and highlight the role of Na as a template for alkyltin Keggin clusters. Unlike other alkyltin clusters that are cationic, β‐NaSn₁₃ is neutral. Consequently, it stands as a unique model system, absent of counterions, to study the transformation of clusters to films and nanopatterns.     

Nanotheranostic fabrication of iron oxide for rapid photocatalytic degradation of organic dyes and antifungal potential

This research work includes the fabrication of iron oxide nanoparticles (Fe₂O₃ NPs) by green construction approach using Wisteria sinensis leaves extract. Due to its eco-friendly approach, the synthesis of iron oxide NPs (Fe₂O₃ NPs) using various plant sources, such as plant parts, and microbial cells have gained a lot of attention in recent years. Cost-effectiveness and ease of availability make Wisteria sinensis leaves extract a potential candidate for the construction of iron oxide NPs. The various key features like biocompatibility, non-toxicity capping, and stabilizing agents present in biological sources are advantageous for usage in a variety of applications. The phytoconstituents present in the leaf extract of Wisteria sinensis serve as reducing and stabilizing agents. The biologically fabricated (Fe₂O₃ NPs) were analyzed using FT-IR, XRD, UV–vis spectroscopy, and SEM. In the present work, the antioxidant and photocatalytic dye degradation efficiency of Fe₂O₃ NPs has been studied. The dye degradation efficiency of methylene blue dye was found to be 87% at 180 min upon exposure to sunlight. The capacity of Fe₂O₃ NPs to scavenge 2,2-diphenyl-1-picrylhydrazyl hydrate free radicals (DPPH) was examined using a UV–Vis spectrophotometer. The study compared the radical scavenging activity (RSA) of Fe₂O₃ nanoparticles (NPs) with that of the standard antioxidant ascorbic acid. The results demonstrated that Fe₂O₃ NPs have a greater ability to scavenge radicals than ascorbic acid. The half-maximal inhibitory concentration (IC50) of Fe₂O₃ NPs was observed to range from 0.12 to 0.17. Furthermore, Fe₂O₃ NPs displayed the highest antifungal activity, with an inhibition zone of 26.8 mm against F. oxysporum. These findings suggest that the biologically synthesized Fe₂O₃ NPs possess potent antimicrobial and dye degradation properties.     

The role of the cage dimer of formaldehyde in the photolysis of formaldehyde: Argon matrix at 12 K

Photolysis of H₂CO was carried out in an Ar matrix with different matrix ratios (M/R). The infrared (IR) absorption spectra of the initial matrix preparation show that the matrix isolated monomers are almost exclusively present at very high dilutions (M/R or 5000) whereas the cage dimers and higher multimers are present in significant amounts at lower dilutions. The post-photolysis IR spectra indicate that the photodecomposition of H₂CO is mainly effected with the cage dimer, and that CH₃OH and CO are formed as photoproducts. The majority of the photoproducts exist as cage dimers of CH₃OH/CO. Upon thermal annealing after photolysis, diffusion through the matrix leads to the additional formation of aggregates composed of CH₃OH/H₂CO as well as CH₃OH/CO.     

EXAFS characterization of Ti/Al2O3 supports and Co/Ti/Al2O3 catalysts

The structure of Ti/Al₂O₃ supports (0–14 wt% Ti) and Co/Ti/Al₂O₃ catalysts (3 wt% Co) was examined by EXAFS. The results indicated that the Ti was present primarily as a highly dispersed surface phase. The Ti EXAFS results indicated that the Ti species were octahedrally coordinated. Evidence of Ti—Ti interactions was found for all loadings (2–14 wt% Ti) suggesting that the Ti surface species are present as small clusters of TiO₂.The Co EXAFS results showed evidence for several structurally different Co surface phases as a function of Ti loading. Evidence of a Co species interacting with the Ti surface phase was observed for the 3% Co/2% Ti-3%Co/6%Ti catalysts. At the highest loadings studied, 3%Co/8%Ti and 3%Co/14%Ti, evidence was found for a CoTiO₃-like phase.     

Core-hole photoionization study of polysilane compounds

We present the results obtained with a new experimental set-up designed for the study of free semi-conductor clusters. This set-up is aimed to study the mass distribution of particles and the evolution of electronic properties as a function of the size, using the technique of core hole photoionization. The cluster production is based on the technique of radio-frequency discharge decomposition of a gas. We study the gaseous particles (Si _n H _x , 0<x<2n+2) generated by pure silane (SiH₄) discharges at low pressures (<10 millitorr) under continuous RF (Radio-Frequency) excitation conditions. We have studied the neutral species present in the post discharge zone and the positive ions present in the discharge. We identify the neutral species as polysilane compounds. We have also compared the ionization spectra obtained near Si-2p edge for the particles containing few silicon atoms with the spectra of SiH₄ and Si₂H₆ molecules. For these molecules, the experimental observations are in agreement with theoretical calculations.     

Electrochemistry of tellurium(IV) in KCl−AlCl3 melts

The reduction of Te(IV) at tungsten electrodes in basic and neutral KCl?AlCl₃ melts has been studied in the temperature range from 300 to 400°C using cyclic voltammetry and differential pulse polarography. In basic melts Te(IV), present as TeCl₆^2? and TeCl₅^?, is reduced to soluble Te(II) species, which can be further reduced to elementary tellurium insoluble in tungsten. The divalent species are stabilized by increasing the temperature. From the pCl^? dependence of the reduction process, Te(II) in basic melts is suggested to be present as TeCl₃^? and TeCl₂. In neutral melts a third oxidation state (possibly monovalent tellurium) is formed when Te(II) is reduced.