Metal Acetates Research Articles

Novel complexes of 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole with metal acetates and arylchalcogenylacetates

The reaction of 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole (Metronidazole) with salts of biologically active arylchalcogenylacetic acids affords novel perspective physiologically active metal complexes.

Mixed-Metal Oxo Clusters Structurally Derived from Ti6O4(OR)8(OOCR')8.

The mixed-metal oxo clusters FeTi5O4(OiPr)4(OMc)10 (OMc = methacrylate), Zn2Ti4O4(OiPr)2(OMc)10, Cd4Ti2O2(OAc)2(OMc)10(HOiPr)2, [Ca2Ti4O4(OAc)2(OMc)10]n, and [Sr2Ti4O4(OMc)12(HOMc)2]n were obtained from the reaction of titanium alkoxides with the corresponding metal acetates and methacrylic acid. Their structures are derived from Ti clusters with the composition Ti6O4(OR)8(OOCR′)8. The Ca and Sr derivatives consist of chains of condensed clusters.

Adsorption of volatile hydrocarbons in iron polysulfide chalcogels

We report the synthesis, characterization and possible applications of three new metal-chalcogenide aerogels KFe3Co3S21, KFe3Y3S22 and KFe3Eu3S22. Metal acetates react with the alkali metal polychalcogenides in formamide/water mixture to form extended polymeric frameworks that exhibit gelation phenomena. Amorphous aerogels obtained after supercritical CO2 drying have BET surface area from 461 to 573m2/g. Electron microscopy images and nitrogen adsorption measurements showed that pore sizes are found in micro (below 2nm), meso (2–50nm), and macro (above 50nm) porous regions. These chalcogels possess optical bandgaps in the range of 1.55–2.70eV. These aerogels have been studied for the adsorption of volatile hydrocarbons and gases. A much higher adsorption of toluene in comparison with cyclohexane and cyclopentane vapors have been observed. The adsorption capacities of the three volatile hydrocarbons are found in the following order: toluene>cyclohexane>cyclopentane. It has been observed that high selectivity in adsorption is feasible with high-surface-area metal chalcogenides. Similarly, almost an eight to ten times increase in adsorption selectivity towards CO2 over H2/CH4 was observed in the aerogels. Moreover, reversible ion-exchange properties for K+/Cs+ ions have also been demonstrated.

Temperature dependence of complex formation constants in aqueous solutions of metal acetates

The equilibrium constants of formation of inner- and outer-sphere cation-anion complexes (ion pairs) in aqueous solutions of different metal acetates in a wide temperature range have been calculated by integrating the density function of distribution of ligands around the cation. The standard Gibbs energies, enthalpies, and entropies of formation of 1: 1 complexes have been calculated. It has been shown that, in all solutions under consideration, contact and solvent-separated ion pairs coexist. A conclusion has been drawn that the temperature dependence of ion association constants is mainly determined by the temperature dependence of the water dielectric constant.

Direct Correlation of the Morphologies of Metal Carbonates, Oxycarbonates, and Oxides Synthesized by Dry Autoclaving to the Intrinsic Properties of the Metals

Dry autoclaving of the metal acetates under similar conditions resulted in various phases and morphologies of metal carbonates, oxycarbonates, and oxides. The acetates of calcium (Group IIA) gave ∼100 nm thick CaCO3 nanosheets, and 3d transition metals (Mn and Fe) gave MnCO3 microcubes and Fe3O4 tetragonal bipyramids. The lanthanides (La, Ce, and Pr) presented hierarchical flower-shaped structures with self-assembled 85–250 nm thick nanosheets comprising of La2O2CO3 and LaOHCO3 mixed phases, CeO2 and Pr2O2CO3, respectively. The Gibb’s free energy of formation (ΔGfo) of the oxide or decomposition of the carbonates at elevated temperatures >700 °C controls the final phase. Elemental line scans showed carbon coating on the nanosheets, whereas carbon existed as separate microspheres whenever the micron-sized morphologies were obtained. The solidification kinetics of the supercritical metal intermediates and carbon were comparable when the freezing point (FP) of the metals is <1000 °C such that once the nanosheets formed from stacking of the solidified nuclei, carbon could wrap and stabilize the nanosheets. The autoclaved products were air heated to obtain the metal oxide phases. Defect-related emissions were observed from the rare-earth oxides.

Improving ion current of sparkplug ion sensors in HCCI combustion using sodium, potassium, and cesium acetates: Experimental and numerical modeling

Measuring the ion current with a sparkplug ion sensor in a homogeneous charge compression ignition (HCCI) engine can be used to investigate the ion chemistry in the cylinders during combustion. HCCI engines are similar to a well-stirred reactor and operate at lean equivalence ratios (ϕ). Under these conditions, the ion current becomes increasingly indistinguishable from background noise. This paper investigates various fuel additive effects on ion signal at low ϕ’s, determines side effects of metal acetate addition, and validates a numerical model. The fuel additives added to ethanol were sodium acetate (NaOAc), potassium acetate (KOAc), and cesium acetate (CsOAc). Concentration levels ranging from 0.5 to 4.9mmol/L of metal acetate-in-ethanol are investigated over ϕ’s 0.11, 0.22, 0.28, and 0.32. The engine operated under naturally aspirated conditions and maintained a constant timing of 2.5° after top-dead-center (ATDC) at the crank angle degree (CAD) where 50% of the heat release occurs (CA50). CsOAc consistently produced the strongest ion signals, followed by KOAc and NaOAc, which NaOAc had the weakest effect on ion signal. No distinguishable ion signals were measured at ϕ=0.11, but significant ion signal improvements occurred at ϕ=0.22 using the fuel additives. However, the addition of the metal acetates decreased heat release rates (HRR) and peak cylinder pressures. Although CsOAc produced the largest signal improvements, it also had the largest decrease in HRR and peak cylinder pressure. Additionally, a single-zone engine model that simulates the chemical kinetics and ion chemistry of KOAc addition is presented and validated with the experimental results.

The Field-Dependent Magnetization of d5–d7 Metal β−Diketonate Complexes and Their Macromolecular Polymers

A vibrating sample magnetometer (VSM) has been used to study the field-dependent magnetization, M(H), of the d5−d7 metal acetates [M(OAc)2.nH2O], metal β−diketonate complexes [M(tba)2(H2O)2] and the macromolecular polymers [M(tba)2(4,4-bipy)]n (where, M = Mn(II), Fe(II), and Co(II), OAc = O2CCH3, tba = deprotonated 3-benzoyl-1.1.1-trifluoroacetone, and 4,4-bipy = 4,4′-bipyridine). The magnetic field strength (H) was applied in the range of 0−104 Oe at ambient temperature (ca. 23°C). The experimental results showed that the d5−d7 metal acetate, complexes and polymers exhibit low paramagnetic properties excepting [Fe(tba)2(4,4-bipy)]n polymer, which had negative magnetization M(emu/g) showing diamagnetic properties in the range 0−104 Oe. The magnetization was almost equal to zero without an applied magnetic field (H(Oe)) for each d5−d7 metal acetate, complex, and polymer. The linear M(H) curve had a magnetic saturation for iron and manganese acetate species at the magnetic field strengths of 3.1 × 103 and 4.7 × 103 Oe, respectively. The external magnetic field reached 9.0 × 103 Oe without any saturation magnetization for the cobalt compounds. The coordination effect of 3-benzoyl-1.1.1-trifluoroacetone (H-tba) and 4,4′-bipyridine (4,4′-bipy) ligands on the field-dependent magnetization M(H) and paramagnetic behavior of d5−d7 metal atoms is discussed. The field-dependent magnetization M(H) curves of metal β−diketonate complexes and the polymers including d5−d7 metal acetates showed a weak field octahedral geometry.

ChemInform Abstract: 4,2′:6′,4′′‐Terpyridines: Diverging and Diverse Building Blocks in Coordination Polymers and Metallomacrocycles

AbstractReview: 44 refs.

Transparent conductive thin films of Cd2SnO4 obtained by the sol–gel technique and their use in a solar cell made with CdTe

In this work Cd2SnO4 polycrystalline thin films with cubic phase were deposited on glass substrates by the sol–gel technique starting from the mixture of two simple precursor solutions of CdO and SnO2, obtained at room temperature. Both solutions were prepared using metallic salts, cadmium acetate and stannous chloride. The Sn atomic concentration percentages (X) in the precursor solution with respect to Cd (1−X) were 16, 25, 29, 33, 36 and 40. The films were sintered at 550°C in air and, after that, exposed to two different annealing treatments, 96/4N2/H2 gas mixture and vacuum, at 350°C and 550°C, respectively. X-ray diffraction patterns of the films without annealing showed three types of films: i) for X<29at%, the films were constituted of CdO+Cd2SnO4 crystals, ii) for X=29at% and X=33at%, Cd2SnO4 polycrystalline thin films were obtained, and iii) for X>33at%, Cd2SnO4+ CdSnO3 crystals were formed. Cd2SnO4 films maintained the spinel-type crystalline structure of the Cd2SnO4 after the annealing processes. On the other hand, Electron Dispersion Spectroscopy measurements revealed that Cd2SnO4 films obtained at X=29at%, without annealing, had a Cd/Sn ratio nearest to the one of the Cd2SnO4 compounds. With and without annealing Cd2SnO4 films showed high optical transmission ~85% in the 500nm<λ<1500nm range. A minimum resistivity value was around 2×10−3Ωcm, which was obtained for Cd2SnO4 films (X=33at%) annealed in vacuum at 550°C, and a direct band gap energy value of 3.55eV. As a test of the quality of these films as transparent electrodes, Au/Cu2Te/CdTe/CdS/Cd2SnO4/glass solar cells were obtained with average efficiency of 10.7%.

Structurally diverse copper complexes bearing NNO-tridentate Schiff-base derivatives as efficient catalysts for copolymerization of carbon dioxide and cyclohexene oxide.

Structurally diverse copper acetate complexes based on NNO-tridentate Schiff-base ligands were synthesized and characterized as mono-, di-, and trinuclear complexes with respect to varied ancillary ligands. Treatment of the ligand precursors (L(1)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-4-methylphenol, L(2)-H = 4-chloro-2-(1-((2-(dimethylamino)ethyl)imino)ethyl)phenol, and L(3)-H = 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methylphenol) with Cu(OAc)2·H2O (1 equiv) in refluxing ethanol afforded five-coordinate mono- or bimetallic copper complexes ([(L(1))Cu(OAc)(H2O)] (1); [(L(2))Cu(OAc)(H2O)] (2); [(L(3))2Cu2(OAc)2] (3)) in high yields. Dinuclear copper acetate analogue [(L(1))2Cu2(OAc)2] (4) resulted from treatment of L(1)-H as the ligand precursor in refluxing anhydrous MeOH with equimolar proportions of metal acetate salt under a dry nitrogen atmosphere. However, a trinuclear complex, [(L(4))2Cu3(OAc)4] (5), was obtained on utilizing 2-(1-((2-(dimethylamino)ethyl)imino)ethyl)-5-methoxyphenol (L(4)-H) as the proligand under the same synthetic route of 1-3; this complex was also synthesized in the reaction of L(4)-H and copper(II) acetate monohydrate in the ratio of 2:3, giving a quantitative yield. All complexes are active catalysts for copolymerization of cyclohexene oxide (CHO) and CO2 without cocatalysts. In particular, dinuclear Cu complex 3 performed satisfactorily to produce polycarbonates with controllable molecular weights and high carbonate linkages. These copper complexes are the first examples that are effective for both CO2/CHO copolymerization and formation of polymers in a controlled fashion.

Versatile and Low-Toxic Solution Approach to Binary, Ternary, and Quaternary Metal Sulfide Thin Films and Its Application in Cu2ZnSn(S,Se)4 Solar Cells

We developed a versatile and environmentally friendly solution approach for the fabrication of a variety of metal sulfide nanocrystal thin films. Metal oxides, metal hydroxides, metal chlorides, metal acetates, and metal acetylacetonates can be used as the starting materials and dissolved in thioglycolic acid and ethanolamine, forming many types of metal–organic precursor solutions. High quality CdS, SnS, CuInS2, CuSbS2, Cu2ZnSnS4, Cu(In0.7Ga0.3)S2, and luminescent Ag-doped ZnxCd1–xS nanocrystal thin films have been successfully prepared by spin-coating their corresponding metal precursor solutions. Cu2ZnSn(S,Se)4 thin film solar cell with a power conversion efficiency of 6.83% has been realized by this versatile method.

Rapid and Cost‐Effective Synthesis of Nanosized Zeolitic Imidazolate Framework‐7 with N,N′‐Dimethylformamide as Solvent and Metal Acetate Salt as Metal Source

AbstractIn this study, a new method was developed for the rapid and cost‐effective synthesis of nanosized zeolitic imidazolate framework‐7 (ZIF‐7) nanocrystals with a high yield and a low molar ratio of benzimidazole ligand to metal salt (2:1) by using N,N′‐dimethylformamide (DMF) as the solvent and zinc acetate dihydrate (Zn(OAc)2⋅2 H2O) as the metal source. The synthesized ZIF‐7 nanocrystals have a size of approximately 50–80 nm, and tend to aggregate or become intergrown to form irregular nanoparticles of about 200–300 nm in size. The morphology and yield of the ZIF‐7 nanocrystals can be tuned easily by changing the synthetic parameters such as the composition of the solvent and concentrations of reagents. The synthesized ZIF‐7 nanocrystals exhibit good thermal and chemical stability, CO2 capture capability, and fluorescent properties. Remarkably, we find that the synthetic strategy developed here can be extended to the syntheses of other kinds of ZIFs including ZIF‐69 and ZIF‐90. This study offers a new, simple synthetic strategy for the high‐yield preparation of ZIF materials.

Fabrication and Characterization of CuO-ZnO-Cu2O Nano-Composites by Sol-Gel Route: Effect of Calcinations Temperature

Mixed CuO-ZnO-Cu2O nano-composites have been prepared by a sol–gel route using monoethanolamine/isopropanol solutions and metal acetate precursors which is simple and cost effective. The precursor powders were analyzed by thermogravimetry (TG) and differential thermogravimetry (DTG). X-ray powder diffractometry (XRD), infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FESEM) were used to characterize the structural and the chemical features of the nano-composites. It was observed that the crystal structure changed from ZnO-CuO-Cu2O-Cu with 31.6, 5.5, 24.9, 38 (%w/w) at 350°C calcinations temperature to 42.4, 48.7, 6.1, 2.8 (%w/w) at 550°C calcinations temperature. XRD measurements indicated an increase in the ratio of ZnO-CuO while the ratio of Cu2O-Cu was decreased. The ZnO-CuO-Cu2O-Cu nano-composites with different content ratios were formed. The crystalline characteristics depended primarily on the calcinations temperature. These semiconducting composite oxides have potential applications in electronics and optoelectronics. An average nano-crystallite size of 68 nm was obtained as estimated by Scherrer's equation. The optical properties were also investigated using diffuse reflectance (DRS) spectroscopy.

π-Complexes of Tropolone and Its N-Derivatives: Ambidentate [O,O]/[N,O]/[N,N]-Cycloheptatrienyl Pentamethylcyclopentadienyl Ruthenium Sandwich Complexes

Tropolone and its N-derivatives isopropylaminotropone and diisopropylaminotroponimine react with [Cp*Ru(CH3CN)3]PF6 as the source of the electron-rich Cp*Ru+ synthon in a simple “capping reaction” to the first cyclopentadienyl/cycloheptatrienyl sandwich complexes containing two vicinal oxo or amino substituents. These heteroleptic, cationic C5/C7 π-complexes, [Cp*Ru(C7H5)O2H]+ (4), [Cp*Ru(C7H5)O(NiPr)H]+ (5), and [Cp*Ru(C7H5)(NiPr)2H]+ (6), are air-stable 18-electron metallocenes without precedence. In solution, NMR spectroscopy proves the principal π-coordination of the substituted η7-cycloheptatrienyl ligands, whereas in the solid state a η5-cycloheptatrienyl coordination mode with bent oxo/imino moieties prevails, as shown by X-ray single-crystal structure analyses. Chemically, these compounds are the conjugate Bronsted acids of neutral [O,O]-, [N,O]-, or [N,N]-metalloligands. Reaction with metal acetates or acetylacetonates by in situ deprotonation and complex formation gives access to trimetallic (M ...

Size effects in magnetotransport in sol–gel grown nanostructured manganites

We report the results of the studies on polycrystalline nanostructured La0.7Pb0.3MnO3 (LPMO) manganites synthesized using sol–gel method employing metal acetate precursor route. Interestingly, it is observed that crystallite size decreases with increase in sintering temperature while microscopic investigations reveal the second grain growth in all the samples. A correlation between the grain morphology and secondary grain growth with the transport and magnetotransport in LPMO manganites has been established. Observation of large temperature sensitivity (~−28.29 %/K @ 0 T; >300 K) and field sensitivity (~−48.70 %/T @ 0.2 T; 5 K) in the samples sintered at higher temperature (~1150 °C) has been understood in the light of observed secondary grain growth in the form of nanosized grains over the surface of primary grains.

Thermal and Microbicidal Study of Coordination Polymers: Transition Metal with 8HQMIT Ligand

A few coordination polymers of transition metal, Mn(II), Co(II), Ni(II), Cu(II), and Zn(II), obtained from the reaction of metal acetate with newly synthesized bis-indol contains ligand namely, 3,6-bis(1-((8-hydroxyquinolin-5-yl)methyl)-1H-indol-3-yl)-1,2,4-triazin-5(2H)-one (8HQMIT) are described here. The ligand has been characterized by 1H NMR, 13C NMR, IR, and FAB mass spectra. Elemental analysis, infrared and electronic reflectance spectra, magnetic susceptibility measurements, and thermogravimetry have been employed to characterize the coordination polymers. The coordination polymers have distorted octahedral geometry. The microbicidal activity of all the samples has also been monitored against plant pathogens. The thermal decomposition of the coordination polymers is studied and indicates that not only the coordinated water is lost but also that the decomposition of the ligand from the coordination polymers is necessary to interpret the successive mass loss.

Properties of Rare-Earth Substitution in Bi(Pb)-2223 Superconductor Prepared by Coprecipitation Method

The superconducting and structural properties of pure and rare-earth elements substituted in Bi (Pb)-2223 samples were investigated. All samples were fabricated by the oxalate coprecipitation (COP) method using metal acetates and oxalic acid as starting materials. The electrical and resistivity were measured by using the four-probe method, while phase purity and microstructural examination were performed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM). The pure sample has a critical temperature of (Tc zero) 100 K, which decreased to 98, 96 and 97 K for the Eu, Dy and Yb samples, respectively. At 77 K, the un-doped sample gives the highest Jc, which gradually decreases with rare-earth substitution as one move towards the right in the lanthanide series. XRD results reveal two main phases (Bi-2223 and Bi-2212) with decreased amounts of Bi-2223 phases by rare-earth substitution. SEM micrographs showed flaky grains but Yb showed better grain alignment compared with the other substitutions.

Synthesis, characterization and DNA photocleavage study of a novel dehydroacetic acid based hydrazone Schiff’s base and its metal complexes

A series of some novel colored complexes of Co(II), Ni(II), Cu(II), Mn(II) and Zn(II) with a novel dehydroacetic acid based hydrazone Schiff’s base has been synthesized and evaluated for their DNA photocleavage potential. The ligand utilized in the present investigation was synthesized via a condensation reaction between cyanoacetic acid hydrazide and dehydroacetic acid. Further, the ligand was treated with different metal acetates of first transition series in 1:1 and 1:2 (metal to ligand) ratios, respectively, to obtain metal complexes with different ligand to metal stoichiometry. Ligand as well as all the synthesized metal complexes were characterized on the basis of data obtained from the techniques like 1H and 13C NMR, IR spectroscopy, mass spectrometry, UV visible spectroscopy, elemental analysis and molar conductance. 1H NMR spectrum of Zn(II) complexes showed the coordination of enolic oxygen atom without deprotonation, but in case of DLCu, the deprotonation of enolic proton was occurred prior to coordination. IR data revealed the participation of a carbonyl oxygen atom of ligand in coordination with metal ions. UV visible data confirmed the square-planar and octahedral geometry of the complexes. Mass spectrum showed the formation of both 1:1 and 1:2 metals to ligand stoichiometry. Most of metal complexes exhibited very good DNA photocleavage activities.

Synthesis, characterization, and dielectric properties of Y2NiMnO6 ceramics prepared by a simple thermal decomposition route

In attempt to search for an improved material preparation technique, Y2NiMnO6 dielectric material is prepared by a one-step thermal decomposition route where a solution of stoichiometric mixtures of metal acetates is directly heated. Structural characterization by X-ray diffraction and electron diffraction shows that the samples were successfully prepared at relatively low temperature comparing to a standard solid state synthesis. Results from several techniques including thermal analysis, electron microscopy, and X-ray absorption are used to investigate compound formation. It is revealed that metal acetates decompose at 300–350 °C resulting in mixture of several metal oxide intermediates which continue to react to form the desired product. Y2NiMnO6 nanoparticles are first obtained at 800 °C. Later, these nanoparticles agglomerate and grow at higher temperature and/or longer heating time to give larger particle size and more crystallinity. Although the starting reagent contains Mn in 2+ oxidation state, X-ray absorption near edge structure analysis indicates that the obtained Y2NiMnO6 contain Mn and Ni in 4+/3+ and 2+ oxidation states, respectively. Ceramic sample shows large dielectric constant of about 6,000–7,000 at 30–120 °C at 1 kHz. Dielectric constant and dielectric response of the sample are consistent with those reported in other works where different synthetic techniques were used. The activation energy of dielectric relaxation is similar to the energy required to transfer electrons between Ni2+ and Mn4+, thus the observed large dielectric constant is intrinsically related to electronic ferroelectricity due to charge ordering of Ni2+ and Mn4+.

Assembly and Catalytic Properties of Cobalt(II) and Copper(II) Coordination Polymers Based on Bis(imidazole) and Carboxylic Acid Mixed Ligands

AbstractTwo CoII/CuII coordination polymers, [Co(bim)(ip)]n (1) and [Cu3(nip)2(OH)(bim)(H2O)]n (2) [bim = bis(imidazol‐1‐yl)methane, H2ip = isophthalic acid and H2nip = 5‐nitroisophthalic acid], were synthesized by reactions of metal acetate with H2ip or H2nip in the presence of bim ligand under hydrothermal conditions. The polymers were characterized by elemental analyses, IR spectroscopy, TGA, XRPD, and single‐crystal X‐ray diffraction. Compound 1 shows a 2D (4, 4) layer structure with CoII ions at the nodes, which is further extended in to a 3D supramolecular network through C–H···π interactions. Compound 2 manifests a four‐connected {Cu5(OH)2}8+ pentameric kernel, which is bridged by bim ligand molecules and two kinds of nip ligands with different coordination modes. This complex also displays a 2D (4, 4) network, which is constructed from pentanuclear CuII clusters as secondary building unit (SBU). In addition, the catalytic properties of the title compounds for the degradation of congo red were investigated.