Organic Acid Ligands Research Articles

Charged organic ligands inserting/supporting the nanolayer spacing of vanadium oxides for high-stability/efficiency zinc-ion batteries.

Given their high safety, environmental friendliness and low cost, aqueous zinc-ion batteries (AZIBs) have the potential for high-performance energy storage. However, issues with the structural stability and electrochemical kinetics during discharge/charge limit the development of AZIBs. In this study, vanadium oxide electrodes with organic molecular intercalation were designed based on intercalating 11 kinds of charged organic carboxylic acid ligands between 2D layers to regulate the interlayer spacing. The negatively charged carboxylic acid group can neutralize Zn2+, reduce electrostatic repulsion and enhance electrochemical kinetics. The intercalated organic molecules increased the interlayer spacing. Among them, the 0.028EDTA · 0.28NH4 + · V2O5 · 0.069H2O was employed as the cathode with a high specific capacity (464.6mAhg-1 at 0.5Ag-1) and excellent rate performance (324.4mAhg-1 at 10Ag-1). Even at a current density of 20Ag-1, the specific capacity after 2000 charge/discharge cycles was 215.2mAhg-1 (capacity retention of 78%). The results of this study demonstrate that modulation of the electrostatic repulsion and interlayer spacing through the intercalation of organic ligands can enhance the properties of vanadium-based materials.

Mechanistic insight into the coke formation tendency during upgradation of crude oil in slurry phase batch reactor using MoS2 and its various oil soluble catalysts

This work intends to provide a deep insight on how can the MoS2 and its oil soluble analogues synthesized using various organic acid ligands (oleate, palmitic acid, lauric acid, stearic acid) efficiently fits well into the landscape of refinery and petrochemical integrations. The slurry phase hydroprocessing of crude oil has been efficiently carried out at 420 °C temperature and 120 bar H2 pressure. The hydroprocessing of crude oil presents the prominent results by increasing the lighter and more valuable fractions in the crude oil, as obtained from SARA analysis result, boiling point distribution, viscosity, sulfur and MCR data. The oil soluble MoS2 catalyst (MLT) synthesized from sodium oleate presented better hydroprocessing activity (65 % VR conversion) than other catalysts due to the small crystallite size, greater hydrophobic interaction, low stacking number and slab length. In this study, the comprehensive analysis of the solid coke obtained from both thermal and catalytic reactions are conducted using the XRD to get various structural parameters (average layer distance between two aromatic sheets (dm), average inter-chain layer distance (dλ), average perpendicular height of stack of aromatic sheets (Lc), average diameter of aromatic sheet (La), and average number of stacked aromatic sheets (M)) to elucidate the coke formation mechanism. These findings highlight the crucial role of catalysts in activating supplied hydrogen gas and promoting the hydrocracking reactions.

Synthesis, Structure, and Magnetic Properties of Two {Co16IICo4III} Supertetrahedral T4 Clusters Formed from the In Situ Dissociation of a Tertiary N-Containing Ligand

Two mixed-valent cobalt clusters {[(CoII)16(CoIII)4(μ6-O)4(μ3-OH)12(OCH3)12(H2O)8(BMBC)4]·(NO3)8} (1) and {[(CoII)16(CoIII)4(μ3-OH)20(OCH2CH3)4(HOCH2CH3)8(BMBC)4]·(NO3)8} (2) were synthesized and constructed by a semiflexible dicarboxylic ligand 4′,4′-[ammoniobis(methylene)]-bis[(1,1′-biphenyl)-2-carboxylate] (BMBC–) with Co(NO3)2·6H2O under solvothermal systems. Interestingly, the ligand BMBC- is afforded from the in situ dissociation reaction of tertiary N-containing organic carboxylic acid ligands. The complexes present a beautiful supertetrahedral T4 cluster formed by an interior Co4IIIO4 cubane and four exterior Co4IIO4 cubanes bridged via μ6-O2 and μ3-OH– ions and stabilized by four BMBC– organic ligands. The complexes were confirmed by single-crystal X-ray diffraction (XRD), elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Furthermore, the magnetic analyses reveal that the [Co20] cluster exhibits an antiferromagnetic behavior.

New Carbamoyl Surface-Modified ZrO2 Nanohybrids for Selective Au Extraction from E-Waste

Efficient and selective extractions of precious and critical metal ions such as Au(III) and Pd(II) were investigated using zirconia nanoparticles surface modified with different organic mono- and di-carbamoyl phosphonic acid ligands. The modification is made on the surface of commercial ZrO2 that is dispersed in aqueous suspension and was achieved by optimizing the Bronsted acid-base reaction in ethanol/H2O solution (1:2), resulting in inorganic-organic systems of ZrO2-Ln (Ln: organic carbamoyl phosphonic acid ligand). The presence, binding, amount, and stability of the organic ligand on the surface of zirconia nanoparticles were confirmed by different characterizations such as TGA, BET, ATR-FTIR, and 31P-NMR. Characterizations showed that all the prepared modified zirconia had a similar specific surface area (50 m2.g-1) and the same amount of ligand on the zirconia surface in a 1:50 molar ratio. ATR-FTIR and 31P-NMR data were used to elucidate the most favorable binding mode. Batch adsorption results showed that (i) ZrO2 surface modified with di-carbamoyl phosphonic acid ligands had the highest adsorption efficiency to extract metals than mono-carbamoyl ligands, and (ii) higher hydrophobicity of the ligand led to better adsorption efficiency. The surface-modified ZrO2 with di-N,N-butyl carbamoyl pentyl phosphonic acid ligand (ZrO2-L6) showed promising stability, efficiency, and reusability in industrial applications for selective gold recovery. In terms of thermodynamic and kinetic adsorption data, ZrO2-L6 fits the Langmuir adsorption model and pseudo-second-order kinetic model for the adsorption of Au(III) with maximum experimental adsorption capacity qmax = 6.4 mg.g-1.

Mobilization and fractionation of rare earth elements during experimental bio-weathering of granites

Weathering of parent granite is pivotal in the formation of regolith-hosted rare earth elements (REE) deposits, which provide over 90 % of global heavy rare earth elements (HREE) demand. Microbes have been recognized to control the fates of REE during weathering jointly with other geochemical factors, but the specific mechanisms of how microbes affect REE mobilization and fractionation remain poorly understood. In this study, bio-weathering experiments at room temperature were conducted with four native bacterial isolates from the Dabu regolith-hosted HREE deposit to investigate the microbial effects on REE mobilization from the parent granite. The presence of these isolates remarkably enhanced the liberation of REE by a factor of 4–21 at the end of the 30-day experiments. Concomitantly, microbes could immobilize REE through extracellular metabolites-induced precipitation and, to a lesser extent, by cell sorption, resulting in 25 %–82 % underestimations of the REE release efficiencies. The synergy of acidolysis and complexation was found to be a crucial bio-weathering mechanism, and complexation with organic acid ligands was more efficient in mobilizing REE at weakly acidic to near-neutral pH. REE fractionation during bio-weathering was mainly controlled by the properties of the host minerals but also influenced by microbes. Specifically, the preferential dissolution of synchysite-Y and parisite-Ce at the initial stage of granite weathering resulted in relatively higher release efficiencies of light rare earth elements (LREE) and middle rare earth elements (MREE). In addition, the secretion of ample organic acids, malic and tartaric acids, in particular, accounted for the preferential release of MREE and HREE mediated by the two isolates from the Bacillus genus. Our results showcase high potential microbial effects on the mobilization and fractionation of REE during granite weathering, posing new sights into the biogeochemical process during the formation of regolith-hosted REE deposits.

Two new Cd(II) MOFs as signal magnifiers for fluorescence detection of levofloxacin

Based on Cd(II) and the new ligand 1,4-bis(5,6-dimethyl-1-(pyridin-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)butane (L), two Cd(II) metal-organic frameworks with molecular formulae [Cd(L)(TPA)·4H2O]n (1) and [Cd(L)0.5(DCTP)·4H2O]n (2) (H2TPA = terephthalic acid, H2DCTP = 2,5-dichloroterephthalic acid) were synthesized by changing the organic carboxylic acid ligands under hydrothermal conditions. 1 displays a 2D hcb layer, whereas 2 exhibits a 3D mog framework. Both 1 and 2 display highly thermal and chemical stability. 1 and 2 are excellent sensors for the detection of levofloxacin via fluorescence enhancement.

Enhancing the interaction between Mn and Ce oxides supported on fly ash with organic acid ligands interface modification for effective VOC removal: A combined experimental and DFT + U study

This work reports a procedure for increasing VOC removal from flue gas using binary oxides (Ce-Mn) supported on fly ash by facile mechanochemical synthetic method in the presence of a solid organic acid ligand (OAL). The presence of OAL during the synthesis process helped produce larger and more accessible particle surface areas, by generating an abundance of micro-/meso porous structures. Meanwhile, the Ce-Mn interaction was enhanced in the catalyst produced (Ce-Mn-OFA) by the presence of OAL during the milling process, yielding a higher ratio of Mn3+/Mn4+ and Ce3+/Ce4+, more lattice defects and surface oxygen vacancies, and greater lattice oxygen mobility. The resulting changes in the fly ash properties substantially improved the oxidation and adsorption activity of Ce-Mn-OFA thus enhancing the catalyst’s potential for VOC removal. The Ce-Mn-OFA catalyst showed the highest catalytic activity for benzene, toluene, m-xylene, and ethylene, which reached 90% conversion at 283 °C, 237 °C, 216 °C, and 264 °C, respectively. More importantly, the presence of the OAL increased the reactive oxygen species and acid sites on the surface of Ce-Mn-OFA, thus weakening the inhibiting effect of NO, NH3, H2O, and SO2 on the VOCs oxidation process. Furthermore, when Ce-Mn-OFA was applied using a special injection system to a large-scale pilot unit, the total concentration of 12 VOCs in the flue gas was reduced from 1347.3 μg/m3 to 131.2 μg/m3. The main contributions of the present work can be summarized as follows: 1) Providing a facile and environmentally friendly new process for the preparation of a heterogeneous catalyst; 2) Revealing the mechanism by which OAL enhances the activity of Ce-Mn in a binary metal oxide catalyst; 3) Evaluating the performance of Ce-Mn-OFA in a real flue gas, which provides feasibility support for its industrial application, such as in coal-fired power plants.

Dimensional Reduction ofEu‐Based Metal‐OrganicFramework as Catalysts for Oxidation Catalysis of C(sp3)–H Bond

Comprehensive SummaryDeveloping new catalysts for highly selectivity and conversion of saturated C(sp3)–H bonds is of great significance. In order to obtain catalysts with high catalytic performance, six Eu‐based MOFs with different structural characteristics were obtained by using europium ions and different organic acid ligands, namelyEu‐1~Eu‐6.Eu‐1,Eu‐2andEu‐3featured three‐dimensional structures, whileEu‐4andEu‐5featured two‐dimensional structures. Differently, a one‐dimensional chain structure ofEu‐6was obtained by changing the ligand. All the six MOFs were applied to the catalytic reaction of C(sp3)–H bond, and it was found that the catalytic effect was gradually enhanced with the decrease of dimension and the increase of the size of channels. As expected,Eu‐6showed the highest selectivity (~99%) and conversion (~99%). Moreover, catalytic cycling and stability tests showedEu‐6can be a reliable catalyst.

One Functionalized Polyoxovanadates Hybrid Material Based on Arsonic Acid with Highly Effective Catalytic Property of Sulfides

In this work, a novel 4-aminophenylarsonic acid functionalized polyoxovanadates (POVs) hybrid material, namely, (Me2NH2)4 ·[(L)8(H12V16O32)] (H2L = 4-NH2C6H4AsO3H2) POVs 1 was solvothermally synthesized and fully characterized. The results revealed POVs 1 consists of four similar tetranuclear vanadium clusters bridged by eight organic 4-aminophenylarsonic acid ligands. Remarkably, functionalized hybrid POVs 1 was further investigated as a heterogeneous stable catalyst in oxidation of sulfide derivatives, and exhibited high catalytic activities (yields up to 96.7%). Additionally, the functionalized hybrid polyoxovanadates catalyst can be reused without losing activities after three runs cycle.

Fe-O Clusters Anchored on Nodes of Metal-Organic Frameworks for Direct Methane Oxidation.

Direct methane oxidation into value-added organic oxygenates with high productivity under mild condition remains a great challenge. We show Fe-O clusters on nodes of metal-organic frameworks (MOFs) with tunable electronic state for direct methane oxidation into C1 organic oxygenates at 50 °C. The Fe-O clusters are grafted onto inorganic Zr6 nodes of UiO-66, while the organic terephthalic acid (H2 BDC) ligands of UiO-66 are partially substituted with monocarboxylic modulators of acetic acid (AA) or trifluoroacetic acid (TFA). Experiments and theoretical calculation disclose that the TFA group coordinated with Zr6 node of UiO-66 enhances the oxidation state of adjacent Fe-O cluster due to its electron-withdrawing ability, promotes the activation of C-H bond of methane, and increases its selective conversion, thus leading to the extraordinarily high C1 oxygenate yield of 4799 μmol gcat -1 h-1 with 97.9 % selectivity, circa 8 times higher than those modulated with AA.

Fe‐O Clusters Anchored on Nodes of Metal–Organic Frameworks for Direct Methane Oxidation

AbstractDirect methane oxidation into value‐added organic oxygenates with high productivity under mild condition remains a great challenge. We show Fe‐O clusters on nodes of metal–organic frameworks (MOFs) with tunable electronic state for direct methane oxidation into C1 organic oxygenates at 50 °C. The Fe‐O clusters are grafted onto inorganic Zr6 nodes of UiO‐66, while the organic terephthalic acid (H2BDC) ligands of UiO‐66 are partially substituted with monocarboxylic modulators of acetic acid (AA) or trifluoroacetic acid (TFA). Experiments and theoretical calculation disclose that the TFA group coordinated with Zr6 node of UiO‐66 enhances the oxidation state of adjacent Fe‐O cluster due to its electron‐withdrawing ability, promotes the activation of C−H bond of methane, and increases its selective conversion, thus leading to the extraordinarily high C1 oxygenate yield of 4799 μmol gcat−1 h−1 with 97.9 % selectivity, circa 8 times higher than those modulated with AA.

Crystal structures and magnetic properties of one-dimensional compounds constructed from Mn2(salen)2 building blocks and organic selenite acid ligands

Two new compounds composed of MnIII salen building blocks and organic selenite acid with ClO4− counter anions, namely [Mn2(salen)2(C6H5SeO2)](ClO4)(1) and [Mn2(salen)2(C6H4FSeO2)](ClO4)(2) [salen = N,N′-bis(salicylidene)-ethylenediamine], were synthesized through a one-pot reaction and characterized structurally and magnetically.

Varying the Concentration of Organic Acid and Amine Ligands Allows Tuning between Quantum Dots and Magic-Sized Clusters of CH3NH3PbBr3 Perovskite: Implications for Photonics and Energy Conversion

Metal halide perovskites, such as methylammonium lead halide (CH3NH3PbBr3), have recently attracted tremendous attention due to their outstanding properties and promising applications. Here, CH3NH3...

CrOx Anchored on the Black-TiO2 Surface via Organic Carboxylic Acid Ligand and Its Catalysis in Oxidation of NO

CrOx/black-TiO2 catalysts were prepared by ligand-assisted (citric acid, oxalic acid and ethylenediaminetetraacetic acid) impregnation method. These catalysts were characterized in detail by means of X-ray diffraction, Raman, BET, X-ray photoelectron spectroscopy, H2 and O2(NO) temperature programmed reduction or desorption and in-suit DFTIR spectra. The results indicated that ligands assistance was beneficial for CrOx interacted with oxygen vacancies and O–Ti–O structures. Among all the catalysts, CrOx/black-TiO2/CA (modified by citric acid) revealed excellent catalytic activity and stability for NO oxidation in the temperature range of 200–450 °C. The characterization results exhibited that the interaction existed between CrOx and oxygen vacancies resulting in more Cr6+. Moreover, the strong interaction between CrOx and O–Ti–O was attributed to the modification of carboxylic acid, which increased the content of Cr3+ and chemical adsorption oxygen. High content of chemical adsorption oxygen promoted the adsorption ability of O2, and Cr6+ enhanced the adsorption capacity of NO. Hence, chemical adsorption oxygen and Cr6+ synergistically promoted the NO oxidation.

Preparation and Characterization of a Novel Terbium Complex Coordinated with 10-Undecenoic Acid for UV-Cured Coatings

A UV-cured composite containing a rare earth complex was prepared for this study. First, the photoluminescent terbium complex was synthesized with a long-chain unsaturated fatty acid (10-Undecenoic acid) by a solution precipitation method, resulting in the 10-UA-Tb(III) complex. Its structure was proven by FTIR, elemental analysis, XRD, and TGA. The results indicated that the organic acid ligand successfully coordinated with the Tb3+ ion and that the complex had a chelate bidentate structure. The emission spectrum of the 10-UA-Tb(III) complex indicated that the complex can emit a bright green light with the unique luminescence of the Tb3+ ion. Furthermore, the luminescence properties of complexes with different ratios of Tb3+ and ligand were studied, and the ratio of Tb3+ and the ligand had an obvious impact on the luminescence intensity of the 10-UA-Tb(III) complex. Subsequently, the prepared rare earth complex was doped into a UV-cured coating in different proportions to obtain a UV-cured composite. The morphology of the rare earth UV-cured composite was observed by SEM. The images showed that the rare earth complex was dispersed uniformly in the polymer matrix. Moreover, the composites could emit fluorescence. Additionally, it has good thermal stability and compatibility with the resin. Therefore, these composites should have potential applications in UV curable materials, such as luminescence coatings.

Rhizosphere priming of two near-isogenic wheat lines varying in citrate efflux under different levels of phosphorus supply.

The rhizosphere priming effect (RPE) has been explained from the perspective of microbial responses to root exudates and nutrient availability. This study introduced a chemical process that could also contribute to RPE: root exudates (organic acid ligands) could liberate mineral-protected carbon (C) in soil for microbial degradation. Wheat (Triticum aestivum L.) near-isogenic lines varying in citrate efflux were grown for 6 weeks in a C4 soil supplied with either low (10 μg g-1) or high P (40 μg g-1). Total below-ground CO2 was trapped and partitioned for determination of soil organic C decomposition and RPE using a stable isotopic tracing technique. Mineral dissolution was examined by incubating soil with citric ligand at a series of concentrations. High P increased RPE (81 %), shoot (32 %) and root biomass (57 %), root-derived CO2-C (20 %), microbial biomass C (28 %) and N (100%), soil respiration (20 %) and concentrations of water-extractable P (30 %), Fe (43 %) and Al (190 %), but decreased inorganic N in the rhizosphere. Compared with Egret-Burke, wheat line Egret-Burke TaMATE1B with citrate efflux had lower inorganic N, microbial biomass C (16 %) and N (30 %) in the rhizosphere but greater RPE (18 %), shoot biomass (12 %) and root-derived CO2-C (low P 36 %, high P 13 %). Egret-Burke TaMATE1B also had higher concentrations of water-extractable P, Fe and Al in the rhizosphere, indicating the release of mineral-protected C. In addition, citrate ligand facilitated Fe and Al release from soil, with their concentrations rising with increasing ligand concentration and incubation time. While high P supply increased microbial growth and RPE possibly due to higher total root exudation, citrate efflux from the root might have facilitated the liberation of mineral-bound C, leading to the higher RPE under Egret-Burke TaMATE1B. Mineral dissolution may be an important process that regulates RPE and should be considered in future RPE research.

Ligand-mediated synthesis of colloidal Cs2SnI6 three-dimensional nanocrystals and two-dimensional nanoplatelets

Cs2SnI6 is a variant on tin-iodide solution-processable materials and may lead to a lead-free material for use in next-generation photovoltaic cells and other optoelectronics. So far, only a few studies have been conducted where shape and geometry control of Cs2SnI6 nanocrystals is demonstrated. Here we report a general approach to directly synthesize Cs2SnI6 of two-dimensional (2D) layered nanoplatelets as well as three-dimensional (3D) nanocrystals. The shape of Cs2SnI6 nanocrystals could be engineered into 3D nanoparticles and different 2D nanoplatelets with well-defined morphology by choosing different organic acid and amine ligands via a hot injection process. Moreover, the thickness of layered 2D nanoplatelets could be adjusted by changing the amount of Cs-oleate present during the synthesis. The photoluminescence emission peaks changed from 643 to 742 nm based on nanomaterial shape. Our method provides a facile and versatile route to rationally control the shape of the Cs2SnI6 nanocrystals, which will create opportunities for applications in lead-free optoelectronics.

A water stable metal–organic framework with 1D nanotube pores for 5-fluorouracil delivery and anti-brain tumor activity

The employment of porous carriers for anticancer drug delivery has gained much attention in recent years for their excellent drug-loading capacity and controlled release performance. In this work, by utilizing a rigid organic aromatic carboxylic acid ligand, a new Zn(II)–organic framework {[Zn2(bptc)(H2O)]·(DMAc)3(H2O)4}n (1, DMAc is in short of N,N-dimethylacetamide, H4bptc is in short of biphenyl-3,3′,5,5′-tetracarboxylic acid ligand), with considerable water stability has been prepared using the solvothermal technology. The structural analysis result reveals that complex 1 is constructed from fourfold helical metal chains whose net could be simplified into a (6,8)-connected topology. Moreover, complex 1 shows 1D nanotube channels with a window size of 10.7 × 10.7 A2 along the [001] direction and reveals a large accessible voids of 51.7%. The desolvated 1 (1a) was used to study the loading and releasing of the 5-fluorouracil (5-Fu), which reveals that 1a could uptake around 51.2 wt% of 5-Fu and nearly 85.6% of the absorbed 5-Fu could be released in PBS (7.4 for the pH value) in 100 h at 37 °C. In connection to these, in vitro cytotoxicity of compound 1 together with the anticancer performance of 5-Fu-loaded 1a was evaluated against human oral epidermal cells and human brain tumor cells SF17 via MTT assays.

Co(II) and Cd(II) metal-organic frameworks with a linear 1,4-di(1H-imidazol-1-yl) benzene and V-shaped polycarboxylate acid ligands: Synthesis, magnetic property and discriminating Fe3 + ion in aqueous solution

Reactions of polycarboxylic acid ligands (H3cpa = 3-(4-carboxy-2-methoxyphenoxy) phthalic acid, H3cmp = 4-(4-carboxy-2-methoxyphenoxy) phthalic acid), N-containing ligand (bimp = 1,4-di(1H-imidazol-1-yl) benzene), with cobalt and cadmium salts under diverse reaction conditions have afforded two novel metal-organic frameworks: [Co3(cpa)2(bimp)2]n (1), [Cd2(cmp)(bimp)2]n (2). The V-shape organic polycarboxylic acid ligands play vital roles in determining the final structure and properties of the complexes. Complex 1 has a 3D structure constructed via bimp ligand connecting adjacent 2D layers and complex 2 has a 3D network with right-handed screw. Magnetic susceptibility measurements (χM) for complex 1 has been performed, and revealed predominant antiferromagnetic behavior. Complex 2 has been employed as a type of fluorescent probe to monitor different metal ions, and showed the obviously selective response to Fe3+ ion through luminescence quenching.

Fluorescence Imaging for Ultrafiltration of Individual Nanoparticles from a Colloidal Solution in Track Membranes

We have used fluorescence nanoscopy for direct imaging of adsorption of individual colloidal quantum dots of diameter ~10 nm (spherical core/shell CdSeS/ZnS semiconductor nanocrystals, functionalized by organic oleic acid ligands) in nanopores of a nuclear filter (a polypropylene track membrane with pores of diameter ~500 nm). We have shown that when a colloidal toluene solution passes through the pores of the membrane, the nanoparticles are completely retained at a depth of 10 μm.