Comparative study of different methods for the preparation of tetraamidato- and tetracarboxylatodiruthenium compounds. Structural and magnetic characterization

Solvothermal and microwave assisted synthesis were used as green and very useful alternative methods to obtain new chloridotetraamidatodiruthenium compounds, [Ru(2)Cl(μ-NHOCR)(4)](n) [R = Me-o-C(6)H(4) (1), Me-m-C(6)H(4) (2), Me-p-C(6)H(4) (3)]. The analogous tetracarboxylato complexes [Ru(2)Cl(μ-O(2)CR)(4)](n) [R = Me-o-C(6)H(4) (4), Me-m-C(6)H(4) (5), Me-p-C(6)H(4) (6)] have also been obtained. These synthetic methods allow the use of greener solvents like water or ethanol. Moreover, solvothermal synthesis permits the direct crystallization of the desired complexes, which are extremely insoluble in common solvents, during the synthetic process. Therefore, the crystal structure of all of them has been established using single crystal X-ray diffraction. Complex 1 shows a Ru-Cl-Ru angle of 180° and constitutes the first example of a chloridotetraamidatodiruthenium derivative displaying linear chains in the solid state. In contrast, complexes 2·0.5EtOH, and 3-6 show polymeric arrangements with the diruthenium units linked by chloride ligands, forming zigzag chains with Ru-Cl-Ru angles ranging between 117.03(6) and 121.45(3)°. All of the complexes show magnetic moments at room temperature corresponding to three unpaired electrons in agreement with the σ(2)π(4)δ(2)(π*δ*)(3) ground-state configuration, which indicates a similar magnetic behaviour in amidato and carboxylato derivatives. In the linear arrangement of complex 1 there is a better magnetic communication between diruthenium units (antiferromagnetic coupling, zJ = -10.5 or -8.7 cm(-1)) than the one observed in the zigzag 2-6 complexes (zJ = -1.23 to -5.75 cm(-1)).     

Comparative study of different carbon materials for the preparation of knitted fabric sensors

Cellulose - Fabric-based flexible sensors prepared from carbon materials as conductive media have promising prospects in human motion detection, gesture recognition, and telemedicine services....     

Comparative study of different chromatographic methods for quality control of113mIn-radiopharmaceuticals

Paper chromatography and Gel Chromatography Column Scanning technique (GCS) have been applied for the separation of indium fractions in^113mIn-radiopharmaceuticals. By these techniques the percentage of ionic indium,^113mIn-colloid and^113mIn-compound have been determined. The resolution efficiency of the gels was found to be significantly influenced by the gel type media and the pH of the eluent. The results obtained from the GCS-profiles indicated that the Sephadex G-50 Fine was the best and can be routinely used in the radiochemical quality control of the^113mIn-phytate. Good separation of^113mIn-colloids,^113mIn-microaggregate and^113mIn-phytate from carrier-free^113mIn-eluate was performed using Whatman No. 3, previously washed with 0.04N HCl and developed either with 0.9% NaCl (for^113mIn-colloid), or 85% methanol (for^113mIn-phytate), or phosphate-methanol buffer (for^113mIn-microaggregate) as rapid and simple procedure for determination of the radiochemical quality control of indium compound in the forms of radiocolloids.     

Comparative study of imprinted polymer particles prepared by different polymerisation methods

To date, imprinted polymers in the form of particles are reportedly made by various polymerisation methodologies, each of them developed to suit specific targets. Polymers made by different methods have, so far, never been directly compared and tested under the same conditions to assess their potential rebinding characteristics, and hence the effect of the production method on the performance of the final imprinted material.In this comparative study, polymers with a similar composition were synthesised by bulk, suspension, emulsion, two-step swelling and precipitation polymerisation. The resulting imprinted materials were characterised physically and their capacity to rebind propranolol under identical analytical conditions was assessed from organic and aqueous solutions by radioligand binding. The results showed that, when specific rebinding of ligand was measured in an organic solution (toluene+0.5% acetic acid), the methods compared as follows: precipitation (50%) > suspension (40%) > bulk (35%) > core-shell (15%) > two-step swelling (10%). When specific rebinding from an aqueous solution (sodium citrate % acetic acid + 2% ethanol, pH 4.6) was measured, the results were somewhat different: two-step swelling (20%) ≅ suspension (19%) ≅ bulk (19%) > core-shell (15%) > precipitation (0%).     

Comparative study of capsaicin molecularly imprinted polymers prepared by different polymerization methods

In this study, the molecularly imprinted polymers (MIPs) of capsaicin are prepared by bulk polymerization (MIPs1), precipitation polymerization (MIPs2), and surface imprinting technology based on SiO₂/Fe₃O₄ particles (MIPs3), respectively. MIPs are characterized by scanning electron microscopy and fourier transform infrared spectroscopy. The adsorption kinetics and thermodynamics of these composites are also investigated to estimate their capacity to rebind capsaicin. The adsorption kinetics show that the adsorption process of MIPs1 is fitted to pseudo first‐order kinetic model, while the kinetic properties of MIPs2 and MIPs3 are well described by pseudo second‐order kinetic model. Adsorption thermodynamics analysis indicated that there are two kinds of binding sites with different affinity in each MIPs, whereas only one kind of binding site in non‐imprinted polymers. All adsorption isotherms of MIPs are fitted to Freundlich models, illustrated that binding sites are distributed heterogeneously in the surface of the materials, and the adsorption might occur in the multimolecular layers. Comparisons of experimental data of three MIPs are achieved and the results show that MIPs3 has the best affinity and absorption capacity to capsaicin. Moreover, the MIPs3 maintain the magnetic properties of Fe₃O₄ particles, which will be applied to the rapid separation of capsaicin from chili peppers samples. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 157–164     

Comparative borazarobenzenes calculations following different methods

Borazarobenzenes are studied with different approaches, some treating only electrons and others including all valence electrons. The importance of the total net electronic density for interpreting the chemical behaviour of the molecules is stressed. All methods agree in assigning fairly high values to dipole moments. Disagreeing conclusions about other properties in the different methods are analyzed.

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Zusammenfassung Die Borazarobenzol-Isomeren werden mit verschiedenen Methoden untersucht, die entweder nur die -Elektronen oder alle Valenzelektronen behandeln. Die Wichtigkeit der Gesamt-Elektronen-dichte für die Erklärung des chemischen Verhaltens der Moleküle wird hervorgehoben. Alle Methoden stimmen in dem Ergebnis recht hoher Werte für die Dipolmomente überein. Unterschiedliche Ergebnisse bei der Anwendung der verschiedenen Methoden werden analysiert.

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Résumé On étude les borazarobenzènes suivant de diverses méthodes; les unes traitent seulement les électrons et les autres impliquent tous les électrons de valence. On souligne l'importance des charges nettes totales pour interpréter le comportement chimique des molécules. Toutes les méthodes s'accordent en attribuer des valeurs assez hautes au moment dipolaire. On analyse des conclusions discordantes sur d'autres propriétés prévues par les différents méthodes.

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One of us (M. G.) wishes to thank the Consiglio Nazionale delle Ricerche for making possible his stay in Italy.     

Comparative study on the photocatalytic properties of Ag3PO4 fabricated by different methods

Research on Chemical Intermediates - A comparative study was carried out on the photocatalytic properties depending on Jodifferent morphologies of Ag3PO4 fabricated by different methods, i.e. as...     

Comparative study of different application methods of 14C-Fosthiazate in tomato plants

A comparative study of different application methods of nematicide ¹⁴C-Fosthiazate was done for the uptake in tomato plants in two varieties Pusa Ruby and Pusa Early Dwarf. The application methods used for the research purpose are seed treatment, soil supplication and drip application in presence and absence of surfactant (Tween-80).It as found that percent absorption was the highest in the drip irrigation method in presence of surfactant. The percent uptake of ¹⁴C-Fosthiazate in two varieties of tomato plants was found to be higher in Pusa Early Dwarf in all the treatment methods.     

An ab initio study of the electronic spectrum of dichlorocarbene CCl2

The lower-lying electronic states of dichlorocarbene have been studied by ab initio methods at different levels of accuracy. For the ¹B₁ ← ¹A₁ transition, the calculated transition energy (1.95 eV) is in good agreement with the gas-phase value (2.10 eV) of Predmore, Murray and Harmony. The discrepancy with the previous CI study by Ha. Gremlich and Bühler is commented on. The vibrational frequencies of CCl₂ in both ¹A₁ and ¹B₁ states were calculated and compared with experiment. The first four triplet and four cationic states have also been examined.     

Comparative study of Co3O4-ZSM-5 catalysts synthesized by different hydrothermal methods for the catalytic oxidation of dichloromethane

In this work, various Co₃O₄-ZSM-5 catalysts were prepared by the microwave hydrothermal method (MH-Co₃O₄@ZSM-5), dynamic hydrothermal method (DH-Co₃O₄@ZSM-5), and conventional hydrothermal method (CH-Co₃O₄/ZSM-5). Their catalytic oxidation of dichloromethane (DCM) was analyzed. Detailed characterizations such as X-ray diffractometer (XRD), scanning microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET), H₂ temperature-programmed reduction (H₂-TPR), temperature-programmed desorption of O₂ (O₂-TPD), temperature-programmed desorption of NH₃ (NH₃-TPD), diffuse reflectance infrared Fourier-transform spectra with NH₃ molecules (NH₃-DRIFT), and temperature-programmed surface reaction (TPSR) were performed. Results showed that with the assistance of microwave, MH-Co₃O₄@ZSM-5 formed a uniform core-shell structure, while the other two samples did not. MH-Co₃O₄@ZSM-5 possessed rich surface adsorbed oxygen species, higher ratio of Co³⁺/Co²⁺, strong acidity, high reducibility, and oxygen mobility among the three Co₃O₄-ZSM-5 catalysts, which was beneficial for the improvement of DCM oxidation. In the oxidation of dichloromethane, MH-Co₃O₄@ZSM-5 presented the best activity and mineralization, which was consistent with the characterizations results. Meanwhile, according to the TPSR test, HCl or Cl₂ removal from the catalyst surface was also promoted in MH-Co₃O₄@ZSM-5 by their abundant Brønsted acid sites and the promotion of Deacon reaction by Co₃O₄ or the synergistic effect of Co₃O₄ and ZSM-5. According to the results of in situ DRIFT studies, a possible reaction pathway of DCM oxidation was proposed over the MH-Co₃O₄@ZSM-5 catalysts.     

Comparative results of kinetic data obtained with different methods for complex decomposition steps

A comparative kinetic analysis on the thermal decomposition of tartaric acid and potassium tartrate under non-isothermal conditions was performed. The non-isothermal kinetic parameters were determined by the following four methods: integral isoconversional method suggested by Flynn-Wall-Ozawa (FWO method); differential isoconversional method suggested by Friedman; Budrugeac-Segal method and Non-Parametric-Kinetic (NKP) method suggested by Sempere and Nomen and modified by Vlase and Doca. The comparison of the results obtaining by these methods leads to interesting conclusions. The experimental data were obtained in dynamic nitrogen atmosphere at heating rates of 5, 7, 10, 12 and 15 K min⁻¹. The less speculative kinetic analysis was possible by the NPK method.     

Comparative properties of Amazonian oils obtained by different extraction methods

Pequi (Caryocar brasiliense Camb.), baba?u (Orbignya phalerata Mart.), buriti (Mauritia flexuosa), and passion fruit (Passiflora edulis) oils were studied to determine their antibacterial, antioxidant and cytotoxic activities, as well as their total phenol and carotenoid contents. The fatty acid contents were determined by GC-MS. The three types of passion fruit oils studied were refined, cold pressed or extracted from seeds in a Soxhlet apparatus. The oils thus obtained showed differences in antioxidant activity and carotenoid content, but were similar in regard to total phenols. Buriti and pequi had the highest carotenoid contents, while refined and cold pressed passion fruit oil displayed the highest antioxidant activity. Pequi oil was the only oil to display antibacterial and cytotoxic activity.     

The synthesis of dichlorodiazirine and the generation of dichlorocarbene: spectroscopy and structure of dichlorocarbene ylides

Reaction of 2,4-dinitrophenoxychlorodiazirine (13) with chloride ions affords dichlorodiazirine (4). Photolysis of 4 generates dichlorocarbene. In laser flash photolysis (LFP) experiments, CCl2 forms chromophoric ylides or oxides with pyridine, 2-picoline, thioanisole, and oxygen. Spectroscopic and computational studies of the ylides are reported. The UV spectrum of CCl2 in solution, however, is not observed. It appears possible that CCl2 is rapidly captured by oxygen to afford a chromophoric dichlorocarbene carbonyl oxide. We present a theoretical analysis of this process.     

A search for dichlorocarbene ether solvent interactions

The absolute rate constant of reaction of dichlorocarbene with pyridine and with tetramethylethylene was determined in Freon-113 (CF₂ClCFCl₂), dioxane, and tetrahydrofuran. No evidence of specific solvation was obtained.     

Comparative study of different cyanide-selective air-gap electrodes

The characteristics of four solid-state cyanide-selective air-gap electrodes are described. When a minute volume of dicyanoargentate(I) solution was used as electrolyte, the double-Nernstian response to cyanide concentration was obtained only with the sensors based on silver or silver sulphide. Sensors based on silver iodide or a silver sulphide/iodide mixture displayed the normal Nernstian character shown by cyanide-selective electrodes dipped in solution. A theoretical explanation of the results involves the relevant equilibrium equations and the mass balance.     

Comparative study of different digestion procedures using supplementary analytical methods for multielement-screening of more than 50 elements in sediments of the river Elbe

The suitability of four different digestion procedures, i.e. i.) an aqua regia digestion according to DIN 38 414-S7, ii.) a pressure digestion using HNO₃/HF in PTFE-vessels, iii.) a HNO₃/HF + HCl-pressure digestion in PTFE-vessels and iv.) a HNO₃/HF + HCl-pressure digestion using microwave induction, has been evaluated with regard to the quantitative determination of about 50 elements in environmental samples. Three sediments of the river Elbe and two standard reference materials (MESS-1 and NIST 1645) have been employed. The analytical results from the dissolved samples, obtained using inductively coupled plasma mass- and optical emission spectrometry as well as total reflection X-ray fluorescence spectrometry, have been compared with those obtained by instrumental neutron activation analysis. Only digestion procedures using HNO₃/HF with a subsequent evaporation to dryness and dissolution in HCl have led to appropriate results for a wide range of elements (more than 50 elements in total). Because of its low contamination risk and its time saving, the microwave digestion is preferred. For this digestion procedure the accordance among the different instrumental methods used is high (better than 15% deviation) in general. A few elements (16) could be determined quantitatively only by a single method.