Monthly Archives: September 2023

Synthesis and Characterization of Homoleptic Zintl Anions [(Pn7)M(Pn7)]4− (M/Pn=Pb/As, Zn/Bi)

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Synthesis and Characterization of Homoleptic Zintl Anions [(Pn7)M(Pn7)]4− (M/Pn=Pb/As, Zn/Bi)

Variations of the coordination of nortricyclane-type 7-atom polypnictides to metal ions were achieved upon reactions of either K3As7 with PbI2 in ethane-1,2-diamine and subsequent layering with toluene or by reacting an extraction solution of ‘K5Ga2Bi4’ in pyridine with [ZnPh2] prior to layering with toluene. The two procedures were specific for the respective elemental combinations, and they afforded the second compound exhibiting the rare Bi7 3− ion in the coordination sphere of transition metal ions.


Abstract

The formation and follow-up chemistry of P7 3− has been intensely studied in the recent decades. In contrast, corresponding investigations of its heavier polycyclic polypnictide congeners Pn7 3− (Pn=As, Sb, Bi), especially Bi7 3−, have been done to a much lesser extent. In our report, we add to these rare studies, by reporting new coordination compounds with As7 3− and Bi7 3−, respectively. Addition of PbI2 to a solution of K3As7 in ethane-1,2-diamine (en) afforded the heterometallic cluster anion [(As7)Pb(As7)]4− (with an 8 % co-crystallization of [PbAs15]3− on the same site), in compound [K3.92(crypt-222)4][(As7)Pb(As7)]0.92[PbAs15]0.08 ⋅ 3en (1). A similar reaction of [ZnPh2] with a pyridine (py) solution of the ternary solid ‘K5Ga2Bi4’, which was previously shown to release Ga and polybismuthide units in situ under certain reaction conditions, resulted in the formation of [K(crypt-222)]4[(Bi7)Zn(Bi7)] ⋅ 2.5py (2), comprising the related heterometallic anion [(Bi7)Zn(Bi7)]4−. The former represents the first Pb−As binary Zintl anions obtained via solution chemistry, and the latter adds one more piece to the remarkably rare coordination compounds reported for Bi7 3−.

Insight into the Structure of MOF‐Containing Hybrid Polymeric Microspheres

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Insight into the Structure of MOF-Containing Hybrid Polymeric Microspheres

Polymer science has exploited MOFs for various purposes, which is due to the fact that these structures are ideal platforms for identifying design features for advanced functional materials. The mechanism of polymerization using MOFs is still largely unexplored and the detailed characterization of both materials is essential to understand the important interactions between the components.


Abstract

Polymer science exploited metal organic frameworks (MOFs) for various purposes, which is due to the fact that these materials are ideal platforms for identifying design features for advanced functional materials. The mechanism of polymerization using MOFs, is still largely unexplored and the detailed characterization of both materials in essential to understand the important interactions between the components. In this work modern advanced research methods were used to investigate the properties of MOF-containing hybrid polymeric microspheres. Hydrothermal conversion of CFA-derived iron particles was used to obtain MOF nanostructures, which were then introduced to the structure of hybrid polymer microspheres based on ethylene glycol dimethylacrylate (EGDMA) and triethoxyvinylsilane (TEVS). Chemical structures were confirmed by ATR-FTIR method. To provide information about the elemental composition of the tested materials and for the determination of chemical bonds present in the tested samples XPS method was applied. Morphology was studied using SEM microscopy, whereas porosity was investigated using ASAP technique. Swellability coefficients were determined using typical organic solvents and distilled water. Moreover, the ecological aspect concerning the use of fly ashes deserves to be emphasized.

The Reaction of Muonium with Hydrogen Peroxide in Aqueous Solution

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The Reaction of Muonium with Hydrogen Peroxide in Aqueous Solution

Experimental data on muonium kinetics in water greatly expands the set of experimental data on kinetic isotope effects in the reactions of H atoms with H2O2 and its conjugate base HOO−.


Abstract

Rate constants for the reactions of muonium (Mu) (the ultralight isotope of the hydrogen atom) with H2O2 in H2O and D2O2 in D2O have been determined at various temperatures and pH (pD) values. The data are consistent with the three reactions: , , and the equivalent for the deuterated entities. A significant positive H/D isotope effect was found for the undissociated peroxide, while for the anions the effect was negligible or slightly in the opposite direction. In addition, for concentrated solutions of peroxide a study of the muon spin polarization as a function of applied transverse magnetic field yielded results consistent with the rate constants determined from the direct decay measurements, and indicated that the reaction products are diamagnetic, most likely MuH and MuOH, i. e., no muoniated radical products are formed. These results are potentially relevant for management of the radiolysis products in nuclear industry.

Exposing the Oxygen‐Centered Radical Character of the Tetraoxido Ruthenium(VIII) Cation [RuO4]+

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Exposing the Oxygen-Centered Radical Character of the Tetraoxido Ruthenium(VIII) Cation [RuO4]+

Production of gas-phase [RuO4]+ via oxidation of ruthenium cations by ozone allows for the direct probing of its oxygen-centered radical character by X-ray absorption spectroscopy. Combining experiment and quantum-chemical calculations, the authors show that the oxygen-centered singly occupied molecular orbital (SOMO) is signalized by a low-energy peak at the oxygen K edge, and is quenched upon hydrogenation in closed-shell [RuO4H]+.


Abstract

The tetraoxido ruthenium(VIII) radical cation, [RuO4]+, should be a strong oxidizing agent, but has been difficult to produce and investigate so far. In our X-ray absorption spectroscopy study, in combination with quantum-chemical calculations, we show that [RuO4]+, produced via oxidation of ruthenium cations by ozone in the gas phase, forms the oxygen-centered radical ground state. The oxygen-centered radical character of [RuO4]+ is identified by the chemical shift at the ruthenium M3 edge, indicative of ruthenium(VIII), and by the presence of a characteristic low-energy transition at the oxygen K edge, involving an oxygen-centered singly-occupied molecular orbital, which is suppressed when the oxygen-centered radical is quenched by hydrogenation of [RuO4]+ to the closed-shell [RuO4H]+ ion. Hydrogen-atom abstraction from methane is calculated to be only slightly less exothermic for [RuO4]+ than for [OsO4]+.

Nine‐coordinated Eu3+ Dipicolinate Compounds: Different Crystal Structures and Luminescence Properties as a Function of pH

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Nine-coordinated Eu3+ Dipicolinate Compounds: Different Crystal Structures and Luminescence Properties as a Function of pH

In this comparative study, two different nine-coordinated Eu3+ compounds with [DPA]2− were crystallised. [Eu(DPA)(HDPA)(H2O)2] ⋅ 4H2O and Na3[Eu(DPA)3] ⋅ 14H2O were found to form in all samples, and the ratio between them can be controlled by pH. Despite the presence of both compounds in all samples, this was not evident from luminescence and PXRD data, althhough the data did not show the single crystal data properties.


Abstract

Two compounds, Na3[Eu(DPA)3] ⋅ 14H2O and [Eu(DPA)(HDPA)(H2O)2] ⋅ 4H2O, were created and the structure determined using single crystal X-ray diffraction. The single crystal luminescence properties were compared and related to the Eu3+ coordination geometry. The formation of single crystals from solutions of Eu(CF3SO3)3 and H2DPA was found change with the pH value of the H2DPA solution. Mixtures of Na3[Eu(DPA)3] ⋅ 14H2O and [Eu(DPA)(HDPA)(H2O)2] ⋅ 4H2O were observed with a pH ratio between the two structures. While visual inspection showed that all samples contained both Na3[Eu(DPA)3] ⋅ 14H2O and [Eu(DPA)(HDPA)(H2O)2] ⋅ 4H2O, the PXRD and luminescence data did not immediately reveal that the samples were pure. Having discovered that the samples were indeed mixtures, quantification was attempted by Rietveld refinement of the PXRD data, and the luminescence spectra were compared to those from single crystals. As the data was not found to reveal that the samples were mixtures, even though we knew that this was the case, we must urge caution when inferring structure-property relationships from powder samples. In this case we were able to isolate monophasic systems and do a comparative study, but this requires that the samples are identified as mixtures.

5‐Nitrofuryl‐Containing Thiosemicarbazone Gold(I) Compounds: Synthesis, Stability Studies, and Anticancer Activity

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5-Nitrofuryl-Containing Thiosemicarbazone Gold(I) Compounds: Synthesis, Stability Studies, and Anticancer Activity

The synthesis of four gold(I) [AuClL] compounds containing chloro and biologically active protonated thiosemicarbazones based on 5-nitrofuryl (L=HSTC) is reported. The cytotoxicity of the gold compounds and thiosemicarbazone ligands was evaluated against selected cancer cell lines and compared to that of Auranofin. Read more about the story behind the cover in the Cover Profile and about the research itself (DOI: 10.1002/cplu.202300115).


Abstract

Invited for this month's cover are the collaborating groups of Esteban Rodríguez-Arce from the University of Chile and María Contel from The City University of New York Brooklyn College. The cover picture shows “Supergold“ a very powerful gender neutral warrior with superpowers who fights against cancer! The warrior's golden armor and sword represent the pharmacological power of the gold atom. Engraved on the shield, the gold-thiosemicarbazone molecules are the warrior's coat of arms. Supergold selectively destroys different cancer cells. More information can be found in the Research Article by Esteban Rodríguez-Arce, María Contel, and co-workers.

Structural and electronic engineering of Co‐doped Ni3C nanoparticles encapsulated in ultrathin carbon layers for hydrogen evolution reaction

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With resurgent interest in green hydrogen as a key element in the transition to a renewable-energy economy, developing efficient, earth-abundant, and low-cost catalysts for hydrogen evolution reaction (HER) is becoming increasingly important but is still very challenging. Herein, we report the synthesis of Co-doped Ni3C nanoparticles encapsulated in ultrathin carbon layers (CNCC) by in-situ thermal decomposition of organic-inorganic hybrid as high-performance HER electrocatalysts. Experimental and density functional theory studies evidence that the substantial high-index (113) surfaces in synergy with a few atomic carbon layers contribute significantly to the activity and stability, while the electronic structure of Ni3C is optimized through tuning the Co content to enhance the intrinsic kinetics for HER. The CNCC exhibits excellent HER activities with overpotentials at 10 mA cm−2 (η10) of 102 and 69 mV and Tafel slopes of 74 and 43 mV dec-1 in respective neutral and alkaline media along with a superior stability without noticeable decay up to 100 h. More importantly, the CNCC outperforms the benchmark Pt/C catalyst under high current density (> 38 mA cm-2) in an alkaline electrolyte, showing great potential for practical hydrogen production.

Oxidization and Chain‐Branching Reaction for Recycling HDPE and Mixed HDPE/PP with In‐situ Compatibilization by Ozone‐Induced Reactive Extrusion

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High-density polyethylene (HDPE) and isotactic polypropylene (iPP) are widely used in industrial and residential applications due to their low cost and chemical stability, thus their recycling process can contribute to a circular economy. However, both polymers are non-polar materials, and the incompatibility with most other materials leads to substantially inferior properties of blends. In this work, we propose a flexible compatibilization strategy to improve the compatibility of HDPE/iPP blends. Ozone was adopted to induce reactive extrusion for rapid oxidation of HDPE and chain-branching reactions for both HDPE and HDPE/iPP blends. During extrusion process, ozone oxidizes HDPE effectively in a short time and introduces oxygen-containing groups such as carbonyl and ester group, which improves the hydrophilicity. The addition of trimethylolpropane triacrylate (TMPTA) could promote branching reaction and facilitate the formation of HDPE-g-iPP copolymers, which improved the compatibility for HDPE/iPP. As a result, the impact strength of ozone-modified HDPE and HDPE/iPP blends increased by 22% and 82%, respectively, and the tensile strength also increased. This strategy would have potential applications in the field of sorting-free and solvent-free recycling of waste polyolefin plastics.

The Underlying Catalytic Role of Oxygen Vacancies in Fatty Acid Methyl Esters Ketonization over TiOx Catalysts

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Recently, interest in converting bio-derived fatty acid methyl esters (FAMEs) into added-value products has significantly increased. The selectivity of ketonization reaction in the conversion of the FAMEs has significantly hampered the efficiency of this process. Herein, we prepared catalysts with different levels of oxygen vacancies while the crystal phase remained unchanged. The catalyst with the highest level of oxygen vacancy exhibited the maximum selectivity. The density functional theory (DFT) simulation showed an increase in interatomic distances leading to the formation of frustrated Lewis pairs (FLPs) upon the creation of oxygen vacancies. The surface measurements, type and density of acid sites of the catalysts, showed that the Lewis acid sites enhanced the selectivity for ketone production; while Bronsted acid sites increased the formation of by-products. Moreover, the ketone formation rate was directly proportional to acid density. The findings of this research provide a different approach for catalyst design, based on defects engineering and their effect on the surface activity, which could be used for enhancing the catalytic performance of novel metal oxides.