Pumping through Porous Hydrophobic/Oleophilic Materials: An Alternative Technology for Oil Spill Remediation

Recently, porous hydrophobic/oleophilic materials (PHOMs) have been shown to be the most promising candidates for cleaning up oil spills; however, due to their limited absorption capacity, a large quantity of PHOMs would be consumed in oil spill remediation, causing serious economic problems. In addition, the complicated and time‐consuming process of oil recovery from these sorbents is also an obstacle to their practical application. To solve the above problems, we apply external pumping on PHOMs to realize the continuous collection of oil spills in situ from the water surface with high speed and efficiency. Based on this novel design, oil/water separation and oil collection can be simultaneously achieved in the remediation of oil spills, and the oil sorption capacity is no longer limited to the volume and weight of the sorption material. This novel external pumping technique may bring PHOMs a step closer to practical application in oil spill remediation.     

Alkyl Ammonium Cation Stabilized Biocidal Polyiodides with Adaptable High Density and Low Pressure

The effective application of biocidal species requires building the active moiety into a molecular back bone that can be delivered and decomposed on demand under conditions of low pressure and prolonged high‐temperature detonation. The goal is to destroy storage facilities and their contents while utilizing the biocidal products arising from the released energy to destroy any remaining harmful airborne agents. Decomposition of carefully selected iodine‐rich compounds can produce large amounts of the very active biocides, hydroiodic acid (HI) and iodine (I₂). Polyiodide anions, namely, I₃^?, I₅^?, which are excellent sources of such biocides, can be stabilized through interactions with large, symmetric cations, such as alkyl ammonium salts. We have designed and synthesized suitable compounds of adaptable high density up to 3.33 g cm^?3 that are low‐pressure polyiodides with various alkyl ammonium cations, deliverable iodine contents of which range between 58.0–90.9 %.     

Sponge Phase Producing Porous CeO2 for Catalytic Oxidation of CO

The aggregation behavior of mixtures of the alkaline amino acid L ‐Arginine (L ‐Arg) and bis(2‐ethylhexyl)phosphoric acid (DEHPA) in water was studied in detail. At a fixed L ‐Arg concentration, a phase sequence of micellar phase (L₁ phase), vesicle phase (L_αv phase), planar lamellar phase (L_αl phase), and sponge phase (L₃ phase) was obtained with increasing DEHPA concentration due to changes in the packing parameter. The phase transition of the lamellar structures was determined by freeze‐fracture TEM and ²H NMR spectroscopy. Rheological measurements reflected the phase transition through significant variations of both the elastic modulus and the viscous modulus. Porous CeO₂ materials were produced by utilizing the L₃ phase as template, and the porous CeO₂ exhibited excellent catalytic oxidation activity toward CO due to its high surface area, which provides more active sites for CO conversion.     

Palladium/Copper‐Catalyzed Oxidative Arylation of Terminal Alkenes with Aroyl Hydrazides

An unprecedented oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed under aerobic conditions for the stereoselective synthesis of 1,2‐disubstituted alkenes. A range of aroyl hydrazides underwent palladium/copper‐catalyzed oxidative Mizoroki–Heck reaction with terminal alkenes open to air in a 1:1 mixture of dimethyl sulfoxide and acetonitrile to give structurally diverse 1,2‐disubstituted alkenes in moderate to excellent yields with excellent regio‐ and E‐selectivity. The reaction tolerated a wide variety of functional groups, such as alkoxy, hydroxy, amino, fluoro, chloro, bromo, cyano, nitro, ester, amide, imide, phosphine oxide, and sulfone groups, and, moreover, molecular oxygen and dimethyl sulfoxide were demonstrated to serve as terminal oxidants. This study provides a useful method for the stereoselective synthesis of 1,2‐disubstituted alkenes through direct transformation of the vinylic C?H bonds in terminal alkenes.     

Reactivity of Oxygen Radical Anions Bound to Scandia Nanoparticles in the Gas Phase: CH Bond Activation

The activation of C?H bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O^?.) is an important species in C?H activation. The mechanistic details of C?H activation by O^?. radicals can be well understood by studying the reactions between O^?. containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n‐butane was studied by using a high‐resolution time‐of‐flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n‐butane by (Sc₂O₃)_NO^? (N=1–18) clusters was observed. The reactivity of (Sc₂O₃)_NO^? (N=1–18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc₈O₁₃^?) and 12 (Sc₂₄O₃₇^?). Larger (Sc₂O₃)_NO^? clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc₂O₃)_NO^? (N=1–5) clusters, which were found to contain the O^?. radicals as the active sites. The local charge environment around the O^?. radicals was demonstrated to control the experimentally observed size‐dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O^?. containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the C?H bond activation.     

Cerium‐Based M4L4 Tetrahedra as Molecular Flasks for Selective Reaction Prompting and Luminescent Reaction Tracing

The application of metal–organic polyhedra as “molecular flasks” has precipitated a surge of interest in the reactivity and property of molecules within well‐defined spaces. Inspired by the structures of the natural enzymatic pockets, three metal–organic neutral molecular tetrahedral, Ce‐TTS, Ce‐TNS and Ce‐TBS (H₆TTS: N′,N′′,N′′′‐nitrilotris‐4,4′,4′′‐(2‐hydroxybenzylidene)‐benzohydrazide; H₆TNS: N′,N′′,N′′′‐nitrilotris‐6,6′,6′′‐(2‐hydroxybenzylidene)‐2‐naphthohydrazide; H₆TBS: 1,3,5‐ phenyltris ‐4,4′,4′′‐(2‐hydroxybenzylidene)benzohydrazide), which exhibit different size of the edges and cavities, were achieved through self‐assembly by incorporating robust amide‐containing tridentate chelating sites into the fragments of the ligands. They acted as molecular flasks to prompt the cyanosilylation of aldehydes with excellent selectivity towards the substrates size. The amide groups worked as trigger sites and catalytic driven forces to achieve efficient guest interactions, enforcing the substrates proximity within the cavity. Experiments on catalysts with the different cavity radii and substrates with the different molecular size demonstrated that the catalytic performance exhibited enzymatical catalytic mechanism and occurred in the molecular flask. These amides were also able to amplify guest‐bonding events into the measurable outputs for the detection of concentration variations of the substrates, providing the possibility for metal–organic hosts to work as smart molecular flasks for the luminescent tracing of catalytic reactions.     

Unravelling the Relationship between Raman Enhancement and Photocatalytic Activity on Single Anisotropic Au Microplates

Anisotropic noble‐metal structures are attracting increasing attention because of interesting size‐ and shape‐dependent properties and have emerging applications in the fields of optics and catalysis. However, it remains a significant challenge to overcome chemical contributions and acquire molecular insight into the relationship between Raman enhancement and photocatalytic activity. This study gives visualized experimental evidence of the anisotropic spatial distribution of Raman signals and photocatalytic activity at the level of single nanometer‐thin Au microtriangles and microhexagons. Theoretical simulations indicate an anisotropic spatial distribution and sharpness‐dependent strength of the electric‐field enhancement. Analysis by using statistical surface‐enhanced Raman scattering (SERS) supports this view, that is, Raman enhancement is on the order of corner>edge>face for a single microplate, but SERS measurements at different depths of focus also imply a concentration‐dependent feature of SERS signals, especially at the corners and edges. Similarly, the SERS signals of product molecules in plasmonic photocatalysis also exhibit asymmetrical strengths at different corners of the same microplate. However, by examining the variations in the relative intensities of the SERS peaks, the difference in the photocatalytic activities at the corners, edges, and faces has been successfully calculated and is highly consistent with electric‐field simulations, thus indicating that an increased number of molecules adsorbed at specific sites does not necessarily lead to a higher conversion ratio in noble‐metal photocatalysis. Our strategy weakens the assumed impact of plasmonic local heating and, to a certain extent, excludes the influence of concentration effects and chemical contributions in noble‐metal photocatalysis, thus clearly profiling plasmon‐related characteristics. This study also promises a new research direction to understand the enhancement mechanism of SERS‐active structures.     

Methane Activation by Diatomic Molybdenum Carbide Cations

Metal carbide species have been proposed as a new type of chemical entity to activate methane in both gas‐phase and condensed‐phase studies. Herein, methane activation by the diatomic cation MoC⁺ is presented. MoC⁺ ions have been prepared and mass‐selected by a quadrupole mass filter and then allowed to interact with methane in a hexapole reaction cell. The reactant and product ions have been detected by a reflectron time‐of‐flight mass spectrometer. Bare metal Mo⁺ and MoC₂H₂⁺ ions have been observed as products, suggesting the occurrence of ethylene elimination and dehydrogenation reactions. The branching ratio of the C₂H₄ elimination channel is much larger than that of the dehydrogenation channel. Density functional theory calculations have been performed to explore in detail the mechanism of the reaction of MoC⁺ with CH₄. The computed results indicate that the ethylene elimination process involves the occurrence of spin conversions in the C?C coupling (doublet→quartet) and hydrogen atom transfer (quartet→sextet) steps. The carbon atom in MoC⁺ plays a key role in methane activation because it becomes sp³ hybridized in the initial stages of the ethylene elimination reaction, which leads to much lower energy barriers and more stable intermediates. This study provides insights into the C?H bond activation and C?C coupling involved in methane transformation over molybdenum carbide‐based catalysts.     

α‐Fe2O3 Cubes with High Visible‐Light‐Activated Photoelectrochemical Activity towards Glucose: Hydrothermal Synthesis Assisted by a Hydrophobic Ionic Liquid

A liquid/liquid interfacial reaction system was designed to fabricate α‐Fe₂O₃ cubes. The reaction system uses a hydrophobic ionic liquid containing iron ions ([(C₈H₁₇)₂(CH₃)₂N]FeCl₄) for manufacturing α‐Fe₂O₃ cubes by a novel and environmentally friendly hydrothermal method under low‐temperature conditions (140 °C). The iron‐containing ionic liquid is hydrophobic and can form a liquid/liquid interface with water, which is vital for fabrication of the α‐Fe₂O₃ cubes. Nanomaterials synthesized from hydrophobic iron‐containing ionic liquids show good crystallinity, well‐developed morphology, and uniform size. The effect of different ionic liquids on the morphology of α‐Fe₂O₃ was investigated in detail. [(C₈H₁₇)₂(CH₃)₂N]FeCl₄ is assumed to perform the triple role of forming a liquid/liquid interface with water and acting as reactant and template at the same time. The effect of the reaction temperature on the formation of the α‐Fe₂O₃ cubes was also studied. Temperatures lower or higher than 140 °C are not conducive to formation of the α‐Fe₂O₃ cubes. Their photoelectrochemical properties were tested by means of the transient photocurrent response of electrodes modified with as‐prepared α‐Fe₂O₃ cubes. The photocurrent response of an α‐Fe₂O₃ cubes/indium tin oxide electrode is high and stable, and it shows great promise as a photoelectrochemical glucose sensor with high sensitivity and fast response, which are beneficial to practical applications of nanosensors.