Carboxylate Precursors Research Articles

Creation of Gas-Phase Organo-Uranium Species by Removal of "yl" Oxo Ligands From UO2 2+ Carboxylate Precursor Ions.

These experiments were conducted to measure the diversity of organo-U (IV) and U (III) ions created using multiple-stage tandem MS and collision-induced dissociation of halogen-substituted UVIO2-phenide complexes [UO2(C6H3FX)]+, X = Cl, Br, or I. Samples of UO2(O2C-C6H3FX)2 were prepared by digesting UO3 with appropriate halogen-substituted carboxylic acids in deionized water. Solutions for ESI were created by diluting the digested sample in 50:50 H2O/CH3OH. Precursor ions for multiple-stage tandem MS were generated by electrospray ionization (ESI). Multiple-stage collision-induced dissociation (He collision gas) in a linear quadrupole ion trap mass spectrometer was used to prepare species such as [UIVFX(C≡CH)]+ and UIIIF(C≡CH)]+ for subsequent study of ion-molecule reactions with adventitious neutrals in the ion trap. Multiple-stage CID of the [UO2(C6H3FX)]+, X = Cl, Br, or I, complexes caused removal of both "yl" oxo ligands from of the UO2 2+ moiety to create ions such as [UIVFX(C≡CH)]+ and [UIIIFX]+. For [UIVFXC≡CH]+ and [UIIIFC≡CH]+ products, hydrolysis to generate [UIVFX (OH)]+ and [UIIIF (OH)]+, with concomitant loss of HC≡CH, was observed. CID of [UO2(C6H3FBr)]+ and [UO2(C6H3FI)]+ caused reductive elimination of the respective halogen radicals to generate interesting organo-U (III) species such as [UIIIF(C≡CH)]+ and [UIIIC2]+. The use of "preparative" tandem mass spectrometry and a suite of halogen substituted benzoic acid ligands can be used to remove both oxo ligands of UO2 2+ and generate a group of homologous organo-U (IV) and organo-U (III) ions for studies of intrinsic reactivity.

Efficient, Facile, and Green Synthesis of Ruthenium Carboxylate Complexes by Manual Grinding

Recently, scientists have been developing sustainable processes, and in this context, mechanochemistry is commonly associated with green chemistry for its ability to reduce waste generation from chemical reactions. The well-known acetate complex, diacetate bis(triphenylphosphine) ruthenium(II) [Ru(OAc)2(PPh3)2], is a versatile precursor for preparing active complexes for several catalytic reactions. This report presents an efficient and straightforward manual grinding protocol for the sustainable synthesis of ruthenium carboxylate complexes starting from the commercially available [RuCl2(PPh3)3] and metal carboxylates. This work represents a novel and preliminary investigation into carboxylate precursors’ alternative solventless synthesis route based on manual grinding. To our knowledge, this is the first time [Ru(OAc)2(PPh3)2] has been prepared via a mechanochemical procedure. The synthesis method has also been investigated for other alkali metal carboxylates and yields ranging from 30 to 80% were obtained. A comparison of sustainability and environmental impact between conventional solution synthesis and the grinding route has been carried out using the E-factor and Mass Productivity. While for the acetate complex E-factor and MP were only slightly better compared with the solvent method (3 vs. 4 for E-factor and ~6 vs. 5 for MP), for benzoate higher results were found (1 vs. ~4 for E-factor and 10 vs. 5 for MP).

Tailoring Morphology and Size of Silver Nanoparticles Prepared by Polyol Method by Changing the Structure of Silver Carboxylate Precursor

AbstractSilver nanoparticles are synthesized by reducing silver alkyl carboxylates at their high concentrations with ethylene and propylene glycol without a common use of polymeric dispersants and stabilizers. The effects of alkyl chain structure on the morphology and size of silver particles have been studied by scanning electron microscopy, transmission electron microscopy, powder X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analyses. The carboxylates that have been investigated are silver caprylate, laurate, 2‐butyloctanoate, and 2‐ethylhexanoate. It was found that the reduction temperature of straight‐chain alkyl carboxylates is in the 110–120 °C range. The particles prepared under these conditions are perfectly spherical in shape and their average size varies from 20 to 40 nm. In the case of the branched structure, the reduction process starts at around 80 °C and produces irregularly shaped silver particles with a size of 150 to 450 nm. Possible ways of controlling the parameters of the synthesized nanoparticles are proposed. This study proposes a simple and easily scalable method to prepare silver nanoparticles stabilized by a non‐polymeric stabilizer. The as‐synthesized silver particles may have applications as metallic fillers in ink and paste formulations for 2D and 3D printing to fabricate functional components and devices.

Tuning the Cerium-Based Metal-Organic Framework Formation by Template Effect and Precursor Selection.

The novel metal-organic framework [(CH3)2NH2]2[Ce2(bdc)4(DMF)2]·2H2O (Ce-MOF, H2bdc-terephthalic acid, DMF-N,N-dimethylformamide) was synthesized by a simple solvothermal method. Ce-MOF has 3D connectivity of bcu type with a dinuclear fragment connected with eight neighbors, while three types of guest species are residing in its pores: water, DMF, and dimethylammonium cations. Dimethylamine was demonstrated to have a decisive templating effect on the formation of Ce-MOF, as its deliberate addition to the solvothermal reaction allows the reproducible synthesis of the new framework. Otherwise, the previously reported MOF Ce5(bdc)7.5(DMF)4 (Ce5) or its composite with nano-CeO2 (CeO2@Ce5) was obtained. Various Ce carboxylate precursors and synthetic conditions were explored to evidence the major stability of Ce-MOF and Ce5 within the Ce carboxylate-H2bdc-DMF system. The choice of precursor impacts the surface area of Ce-MOF and thus its reactivity in an oxidative atmosphere. The in situ PXRD and TG-DTA-MS study of Ce-MOF in a nonoxidative atmosphere demonstrates that it eliminates H2O and DMF along with (CH3)2NH guest species in two distinct stages at 70 and 250 °C, respectively, yielding [Ce2(bdc)3(H2bdc)]. The H2bdc molecule is removed at 350 °C with the formation of novel modification of Ce2(bdc)3, which is stable at least up to 450 °C. According to the total X-ray scattering study with pair distribution function analysis, the most pronounced local structure transformation occurs upon departure of DMF and (CH3)2NH guest species, which is in line with the in situ PXRD experiment. In an oxidative atmosphere, Ce-MOF undergoes combustion to CeO2 at a temperature as low as 390 °C. MOF-derived CeO2 from Ce-MOF, Ce5, and CeO2@Ce5 exhibits catalytic activity in the CO oxidation reaction.

Chemically Fueled Supramolecular Materials.

In biology, the function of many molecules is regulated through nonequilibrium chemical reaction cycles. The prototypical example is the phosphorylation of an amino acid in an enzyme which induces a functional change, e.g., it folds or unfolds, assembles or disassembles, or binds a substrate. Such phosphorylation does not occur spontaneously but requires a phosphorylating agent with high chemical potential (for example, adenosine triphosphate (ATP)) to be converted into a molecule with lower chemical potential (adenosine diphosphate (ADP)). When this energy is used to regulate an assembly, we speak of chemically fueled assemblies; i.e., the molecule with high potential, the fuel, is used to regulate a self-assembly process. For example, the binding of guanosine triphosphate (GTP) to tubulin induces self-assembly. The bound GTP is hydrolyzed to guanosine diphosphate (GDP) upon assembly, which induces tubulin disassembly. The result is a dynamic assembly endowed with unique characteristics, such as time-dependent behavior and the ability to self-heal. These intriguing, unique properties have inspired supramolecular chemists to create similar chemically fueled molecular assemblies from the bottom up. While examples have been designed, they remain scarce partly because chemically fueled reaction cycles are rare and often complex. Thus, we recently developed a carbodiimide-driven reaction cycle that is versatile and easy to use, quantitatively understood, and does not suffer from side reactions. In the reaction cycle, a carboxylate precursor reacts with a carbodiimide to form an activated species like an anhydride or ester. The activated state reacts with water and thereby reverts to its precursor state; i.e., the activated state is deactivated. Effectively, the precursor catalyzes carbodiimides' conversion into waste and forms a transient activated state. We designed building blocks to regulate a range of assemblies and supramolecular materials at the expense of carbodiimide fuel. The simplicity and versatility of the reaction cycles have democratized and popularized the field of chemically fueled assemblies. In this Account, we describe what we have "learned" on our way. We introduce the field exemplified by biological nonequilibrium self-assembly. We describe the design of the carbodiimide-driven reaction cycle. Using examples from our group and others, we offer design rules for the building block's structure and strategies to create the desired morphology or supramolecular materials. The discussed morphologies include fibers, colloids, crystals, and oil- and coacervate-based droplets. We then demonstrate how these assemblies form supramolecular materials with unique material properties like the ability to self-heal. Besides, we discuss the concept of reciprocal coupling in which the assembly exerts feedback on its reaction cycle and we also offer examples of such feedback mechanisms. Finally, we close the Account with a discussion and an outlook on this field. This Account aims to provide our fundamental understanding and facilitate further progress toward conceptually new supramolecular materials.

Structural investigations into colour-tuneable fluorescent InZnP-based quantum dots from zinc carboxylate and aminophosphine precursors.

Fluorescent InP-based quantum dots have emerged as valuable nanomaterials for display technologies, biological imaging, and optoelectronic applications. The inclusion of zinc can enhance both their emissive and structural properties and reduce interfacial defects with ZnS or CdS shells. However, the sub-particle distribution of zinc and the role this element plays often remains unclear, and it has previously proved challenging to synthesise Zn-alloyed InP-based nanoparticles using aminophosphine precursors. In this report, we describe the synthesis of alloyed InZnP using zinc carboxylates, achieving colour-tuneable fluorescence from the unshelled core materials, followed by a one-pot ZnS or CdS deposition using diethyldithiocarbamate precursors. Structural analysis revealed that the "core/shell" particles synthesised here were more accurately described as homogeneous extended alloys with the constituent shell elements diffusing through the entire core, including full-depth inclusion of zinc.

Influence of Metal Coordination on the Gas-Phase Chemistry of the Positional Isomers of Fluorobenzoate Complexes.

The fragmentation behaviors of the o-, m-, and p-fluorobenzoate complexes of La3+, Ce3+, Fe3+, Cu2+, and UO22+ were investigated by electrospray ionization mass spectrometry, and the corresponding reaction mechanisms were explored by density functional theory (DFT) calculations. Fluoride transfer product LaIIIFCl3-/CeIIIFCl3- and decarboxylation product LaIIICl3(C6H4F)-/CeIIICl3(C6H4F)- were observed when the carboxylate precursors LaIIICl3(C6H4FCO2)-/CeIIICl3(C6H4FCO2)- were subjected to collision-induced dissociation. The variation in product ratios, which is not obvious in the meta and para cases, qualitatively follows the increasing overall energy barrier and reaction endothermicity of the two-step CO2/C6H4 elimination mechanism, and this aligns with the increase in U-F distance in the ortho, meta, and para decarboxylation product isomers. In contrast, the mass spectra of FeIIICl3(C6H4FCO2)-/CuIICl2(C6H4FCO2)- are dominated by the reduction product FeCl3-/CuCl2- regardless of the fluorobenzoate isomer. DFT/B3LYP calculations show that the two-step CO2/C6H4F elimination pathways are comparable in energy for all three positional isomers. It is energetically more favorable to give the reduction product than the fluoride transfer product, which is opposite to the lanthanum cases. Although the decarboxylation product was observed for all three UVIO2Cl2(C6H4FCO2)- isomers, the ortho isomer behaves more similarly to LaIIICl3(C6H4FCO2)-/CeIIICl3(C6H4FCO2)- as evidenced by the formation of UVIO2FCl2-, and the appearance of UVO2Cl2- in the cases of the meta and para isomers indicates the similarity with FeIIICl3(C6H4FCO2)-/CuIICl2(C6H4FCO2)-. The shorter U-F distance in UVIO2Cl2(o-C6H4F)- causes the decrease in the fluoride transfer barrier and thus makes this process more favorable over o-C6H4F radical loss to give UVO2Cl2-.

Alkaline-Earth Chalcogenide Nanocrystals: Solution-Phase Synthesis, Surface Chemistry, and Stability.

Increasing demand for effective energy conversion materials and devices has renewed interest in semiconductors comprised of earth-abundant and biocompatible elements. Alkaline-earth sulfides doped with rare earth ions are versatile optical materials. However, relatively little is known about controlling the dimensionality, surface chemistry, and inherent optical properties of the undoped versions of alkaline-earth mono- and polychalcogenides. We describe the colloidal synthesis of alkaline-earth chalcogenide nanocrystals through the reaction of metal carboxylates with carbon disulfide or selenourea. Systematic exploration of the synthetic phase space allows us to tune particle sizes over a wide range using a mixture of commercially available carboxylate precursors. Solid-state NMR spectroscopy confirms the phase purity of the selenide compositions. Surface characterization reveals that bridging carboxylates and amines preferentially terminate the surface of the nanocrystals. While these materials are colloidally stable in the mother solution, the selenides are susceptible to oxidation over time, eventually degrading to selenium metal through polyselenide intermediates. As part of these investigations, we have developed the colloidal syntheses of barium di- and triselenides, two among few reported nanocrystalline alkaline-earth polychalcogenides. Electronic structure calculations reveal that both materials are indirect band gap semiconductors. The colloidal chemistry presented here may enable the synthesis of more complex, multinary chalcogenide materials containing alkaline-earth elements.

Hydro-liquefaction of asphaltene catalyzed by molybdenum-nickel bimetallic catalysts in slurry bed

Abstract The aim of this study is to achieve the hydro-liquefaction of asphaltene for the production of liquid fuel. The oil soluble molybdenum catalysts, molybdenum dialkyl dithiophosphate, and nickel carboxylate precursor with different carbon chains, were synthesized. The catalysts were characterized by ICP-OES, TEM and XPS. Their catalytic performance for the hydro-liquefaction of asphaltene to liquid fuels was investigated in a slurry bed reactor by using decalin as hydrogen donor and dispersant. The results show that the bimetal catalytic system composed of molybdenum dialkyl dithiophosphate and caproic acid nickel produces more MoS2 and NiS x active species. The metal contents of which accounts for 81.8 and 81.0 wt% of the total amount of Mo and Ni, respectively, and thus exhibits the best catalytic performance among the catalysts studied. The liquid yield of the asphaltene hydrogenation over the bimetal catalyst is 84.6 wt%, which is much higher than that over other catalysts, and the coke content is only 8.6 wt% under the conditions of 1000 μg/g of total metal addition, 1:1 Mo/Ni metal mass ratio and 1:1 asphaltene/naphthalene mass ratio. The content of saturated and aromatic components in the liquid products of asphaltene hydrogenation of the bimetal catalyst system is 78.9 wt%, which is a high-quality liquid fuel component.

A Permissive Medium Chain Acyl-CoA Carboxylase Enables the Efficient Biosynthesis of Extender Units for Engineering Polyketide Carbon Scaffolds

The selective incorporation of new-to-nature extender units into polyketide synthesis is a highly effective way to engineer their carbon scaffolds. Currently, most atypical extender units are biosynthesized via reductive carboxylation of α,β-unsaturated thioesters catalyzed by crotonyl-CoA reductase/carboxylases or thioesterification of malonates by malonyl-CoA ligases followed by epimerase catalyzed enantiomerization. In this study, we identified an unusual β-subunit (Arm13) of the acyl-CoA carboxylase (ACCase) from the biosynthesis of armeniaspirols. This β-subunit is permissive to the α- and ε-subunits of propionyl-CoA carboxylase to form a fully active ACCase. Distinct from the other regular ACCases in substrate specificity, this ACCase can directly carboxylate medium chain acyl-CoAs ranging from C6 to C9 either with or without terminal substituents, e.g., alkyne or phenyl groups, to produce corresponding alkylmalonyl-CoAs with high catalytic efficiency. By harnessing the power of this ACCase in extender unit biosynthesis, we introduced structural variation into the carbon scaffold of armeniaspirols by feeding corresponding carboxylate precursors. These findings not only enrich the knowledge of the medium chain-specific ACCases but also provide an important biocatalyst for diversifying building blocks, which will greatly facilitate polyketide engineering.

Iron Stearate Structures: An Original Tool for Nanoparticles Design.

Iron carboxylates are widely used as iron precursors in the thermal decomposition process or considered as in situ formed intermediate precursors. Their molecular and three-dimensional (3D)-structural nature has been shown to affect the shape, size, and composition of the resulting iron oxide nanoparticles (NPs). Among carboxylate precursors, stearates are particularly attractive because of their higher stability to aging and hydration and they are used as additives in many applications. Despite the huge interest of iron stearates, very few studies aimed up to now at deciphering their full metal-ligand structures and the mechanisms allowing us to achieve in a controlled manner the bottom-up NP formation. In this work, we have thus investigated the molecular structure and composition of two iron stearate precursors, synthesized by introducing either two (FeSt2) or three (FeSt3) stearate (St) chains. Interestingly, both iron stearates consist of lamellar structures with planes of iron polynuclear complexes (polycations) separated with stearate chains in all-trans conformation. The iron content in polycations was found very different between both iron stearates. Their detailed characterizations indicate that FeSt2 is mainly composed of [Fe3-(μ3-O)St6·xH2O]Cl, with no (or few) free stearate, whereas FeSt3 is a mixture of mainly [Fe7(μ3-O(H))6(μ2-OH)xSt12-2x]St with some [Fe3(μ3-O)St6·xH2O]St and free stearic acid. The formation of bigger polynuclear complexes with FeSt3 was related to higher hydrolysis and condensation rates within the iron(III) chloride solution compared to the iron(II) chloride solution. These data suggested a nucleation mechanism based on the condensation of polycation radicals generated by the catalytic departure of two stearate chains from an iron polycation-based molecule.

Degradation of sulfamerazine by a novel CuxO@C composite derived from Cu-MOFs under air aeration

Most metal-organic frameworks (MOFs) are synthesized from carboxylate and metal precursors by hydrothermal process, which will consume a large amount of solvent and carboxylate. To address this issue, a new strategy for Cu-based MOFs was developed, in which the Cu-based MOFs was obtained by using abundant natural polymer (tannic acid) as one of the precursors and using high-energy ball milling to achieve a self-assembly of tannic acid and copper sulfate. Based on this strategy, a novel Cu-based MOFs derivative (CuxO@C composite) was synthesized by high-temperature sintering of Cu-based MOFs and used for sulfamerazine (SMR) removal via O2 activation. The BET specific surface area and average pore size of CuxO@C composite were 110.34 m2 g−1 and 21.06 nm, respectively, which made CuxO@C composite had the maximum adsorption capacity (Qmax) for SMR of 104.65 mg g−1 and favored the subsequent degradation of SMR. The results from XRD and XPS indicated that CuxO@C composite contained a lot of Cu0 and Cu2O with the sizes of 76.6 nm and 9.8 nm, respectively, which led to its high performance of O2 activation. The removal efficiency of SMR and 90.2% TOC achieved 100% and 90.2%, respectively in the CuxO@C/air system at initial pH of 4.0, air flow rate of 100 mL min−1, CuxO@C dosage of 1 g L−1 and reaction time of 30 min. Reactive species, including H2O2, OH and O2- radicals were detected in the CuxO@C/air system, and OH and O2- were mainly responsible for the degradation of SMR.

Electrografting of Carbon Surfaces with Aliphatic Chains and its Effect on the Rectification of Ferrocene as Redox Probe in Solution.

The mediated oxidation of acetate and octanoate ions in acetonitrile was used to covalently modify carbon surfaces with films bearing saturated aliphatic chains of different length. Film thickness increases proportionally with the length of the aliphatic chain within the carboxylate precursor. The thickest film was obtained from octanoate oxidation and rectification occurs when ferrocene is used as redox probe in acetonitrile solution. This effect increases with the bulky and hydrophobic nature of the supporting electrolyte cations; n-Hx4 N+ >n-Bu4 N+ >Me4 N+ . The combination of the bulky and hydrophobic properties of the supporting electrolyte ions as well as the hydrophobic properties of the electrografted films is the basis of rectification of ferrocene in cyclic voltammetry experiments. This phenomenon was simulated through a CEC mechanism in solution, where the mass transport inside the film channels was emulated through single chemical equilibria.

Cadmium Telluride Nanocomposite Films Formation from Thermal Decomposition of Cadmium Carboxylate Precursor and Their Photoluminescence Shift from Green to Red

This study focuses on the investigation of a CdTe quantum dots (QDs) formation from a cadmium-carboxylate precursor, such as cadmium isostearate (Cd(ISA)2), to produce CdTe QDs with tunable photoluminescent (PL) properties. The CdTe QDs are obtained by the thermal decomposition of precursors directly in the polymer matrix (in situ method) or in solution and then encapsulated in the polymer matrix (ex situ method). In both approaches, the time course of the CdTe QDs formation is followed by means of optical absorption and PL spectroscopies focusing on viable emission in the spectral interval between 520 and 630 nm. In the polymeric matrix, the QDs formation is slower than in solution and the PL bands have a higher full width at half maximum (FWHM). These results can be explained on the basis of the limited mobility of atoms and QDs in a solid matrix with respect to the solution, inducing an inhomogeneous growth and the presence of surface defects. These achievements open the way to the exploitation of Cd(ISA)2 as suitable precursor for direct laser patterning (DPL) for the manufacturing of optoelectronic devices.

Cadmium Telluride Nanocomposite Films Formation from Thermal Decomposition of Cadmium Carboxylate Precursor and Their Photoluminescence Shift from Green to Red

Cadmium Telluride Nanocomposite Films Formation from Thermal Decomposition of Cadmium Carboxylate Precursor and Their Photoluminescence Shift from Green to Red

Synthesis of Monodisperse InP Quantum Dots: Use of an Acid-Free Indium Carboxylate Precursor.

The role of indium carboxylate precursors in the synthesis of monodisperse InP quantum dots was investigated. The reaction between acid-free indium palmitate and tris(trimethylsilyl)phosphine (P(TMS)3) was monitored by using high-temperature 31P NMR, indicating the presence of a single molecular phosphorus species throughout the duration of the reaction. The addition of varying amounts of carboxylic acid and its effects on both the reaction kinetics and the optical properties of InP QDs were studied. In the presence of acid, rapid protonation of P(TMS)3 led to the formation of a mixture of four HxP(TMS)3-x species, resulting in the poorer controlled formation of InP nanocrystals. Upon deposition of a gradated ZnSeS shell on the synthesized InP core, luminescent quantum dots were obtained (QY 67%; PL: FWHM 40 nm).

Zn-Fe-oxide nanostructures of different iron concentrations for multifunctional applications: properties and precursor influence.

Zn-Fe-O nanoparticle systems (Z3F, Z20F and Z60F) were produced by changing the Zn:Fe ratio (0.97 : 0.03, 0.8 : 0.2 and 0.4 : 0.6 in at%, respectively) in Zn(ii)-Fe(iii)-carboxylate precursors. According to X-ray diffraction, Z60F is nearly single-phase ZnFe2O4 (5.9 nm crystallite size), Z20F is a ZnO/ZnFe2O4 nanocomposite consisting of 48.8% ZnFe2O4 (4.7 nm crystallite size), and Z3F is apparently pure ZnO (9.5 nm). We found evidence for a ZnFe2O4 spinel of high inversion degree (80-100%) and with superparamagnetic (SPM) behaviour at room temperature in all three samples by a remarkable correlation between HRTEM, FTIR, XPS, Mössbauer and magnetization analyses. Iron modifies the decomposition process of the precursor and enhances its viscosity, which appears to favour the separation of Zn- and Fe-rich phases. As a consequence, two-phase systems of individual nanocrystals/nanoparticles (ZnO and ZnFe2O4) are formed. The large anisotropy constant, 106-107 erg cm-3, of the ZnFe2O4 nanoparticles and the concentration dependence of their magnetic energy barrier are explained in terms of interparticle interactions interlinked with finite size effects and high inversion degree; these factors also control the other parameters of importance for applications, including the blocking temperature (13-111 K), saturation magnetization (1.08-17.7 emu g-1 at 300 K, 4.6-44.8 emu g-1 at 5 K) and coercivity (85.4-491 Oe at 5 K). Magnetic dynamic results, particularly modelled by the Néel-Brown and Vogel-Fulcher laws, yield fitting parameters which validate the presence of concentration-dependent dipole-like interactions between ZnFe2O4 nanoparticles. A fraction of iron was found in the Fe2+ state, presumably substituting for Zn2+ in zinc oxide; however, the samples behave like ZnFe2O4 SPM nanoclusters/nanoparticles dispersed in a nonmagnetic ZnO particle assembly, rather than Zn(Fe)O dilute magnetic semiconductors. The relevance of the properties of the investigated material for specific applications is highlighted throughout the manuscript.

Generation of powerful organic electron donors by water-assisted decarboxylation of benzimidazolium carboxylates

In situ and easy generation of organic electron donors from water-activation of carboxylate precursors allows OED-promoted intermolecular radical addition reactions.

Penta- and dinuclear carboxylate nickel(II) complexes with pyrazole-based ligands: Syntheses, magnetic properties and DFT calculations

«One pot» reactions of pyrazole-based ligands Hdmpz and PyPz with in situ formed carboxylate precursors led to the formation of mono- and di-aqua-bridged binuclear compounds, as well as pentanuclear hydroxo-bridged compound: [Ni2(μ-OH2)(μ-O2CC(CH3)3)2(O2CC(CH3)3)2(PyPz)2]1, [Ni5(μ3-OH)2(μ-O2CPh)8(PyPz)4].4.73MeCN2, [Ni2(μ-OH2)(μ-O2CPh)2(O2CPh)2(Hdmpz)4]3, [Ni2(μ-OH2)2(μ-O2CPh)(O2CPh)2(Hdmpz)4](O2CPh)∙2.5H2O4 (Hdmpz = 3,5-dimethylpyrazole, PyPz = 2-(5-Methyl-1H-pyrazol-3-yl)pyridine). Compounds were characterized by structural and spectral methods, thermogravimetric analysis and magnetic measurements were also performed. It was noted, that structural motif of forming compounds are determined by the structure of carboxylate precursors formed in situ and properties of N-ligands. Comparison of magnetic measurements data, structural data, and DFT calculations allows us to conclude that in the case of investigated compounds the equilibrium between spin isomers with different multiplicities, close energy values and close geometrical structure can be realized.

The influence of the nature of carboxylate precursors on the composition and tribological performance of copper-containing nanomaterials

In this study, a comparative study of nanomaterials formed during thermolysis at 300 °C of two representative metal carboxylates (copper capronate and valerate) was carried out. The obtained nanoparticles (NPs) were studied using X-ray diffraction, atomic force microscopy and sedimentation analysis. Copper(I) oxide and copper are the main decomposition products of copper capronate. The crystallite size of copper(I) oxide is from 20 to 30 nm, and that of Cu crystallites is from 11.2 to 11.3 nm and is practically independent of the thermolysis time. The decomposition of copper valerate produces copper(I) oxide with a size of 20 to 50 nm, and the dispersion of particles depends on the thermolysis time of the samples. Analysis of copper-containing nanomaterials as additives to lubricants (Ciatim-221 and liquid paraffin) was carried out in terms of their tribological behavior using a pin-on-disc and four-ball machine tribometers. The introduction of copper(I) oxide NPs reduces the friction coefficient of Ciatim-221 lubricant and liquid paraffin by 26% and 39%, respectively. The microstructure of the friction surface depends on the presence of copper oxide NPs in the lubricant and on the nature of the lubricant base.