Counter Cations Research Articles

Dissolution of poorly soluble uranyl phosphate phases in the Metaautunite Subgroup under uranyl peroxide cage cluster forming conditions

Abstract Uranyl phosphate minerals are widespread in uranium deposits and normally exhibit very low solubility in aqueous systems. Uranyl phosphates of the autunite group and metaautunite subgroup impact the mobility of uranium in the environment and have inspired groundwater remediation strategies that emphasize their low solubility. The importance of soluble uranium-bearing macro-anions, including nanoscale uranyl peroxide cage clusters, is largely unexplored relative to solubilization of normally low-solubility uranium minerals. Eight synthetic analogs of metaautunite subgroup minerals have been prepared and placed in various alkaline aqueous solutions containing hydrogen peroxide and tetraethylammonium hydroxide. Each uranyl phosphate studied has a topologically identical anionic sheet of uranyl square bipyramids and phosphate tetrahedra combined with various cations (Li+, Na+, K +, Rb+, Cs+, Mg2+, Ca2+, Ba2+) and water in the interlayer. Uranyl peroxides formed under many of the experimental conditions examined, including solid studtite [(UO2)(O2)(H2O)2](H2O)2 and soluble uranyl peroxide cage clusters containing as many as 28 uranyl ions. Uranyl phosphate solids in contact with solutions in which uranyl peroxide cage clusters formed dissolved extensively or completely. The greatest dissolution of uranyl phosphates occurred in systems that contained cations with larger hydrated radii, Li+ and Na+. The details of the uranium speciation in solution depended on the pH and counter cations provided from the interlayers of the uranyl phosphate solids.

Synthesis, spectral and structural characterization of vanadium lactate, malate and citrate with large counter cation

Vanadium lactate, malate and citrate [Ni(phen)3]2[VV2O4(lact)2]Cl2·20H2O·2EtOH (1), [Ni(phen)3][VIVO(mal)(phen)]Cl·14H2O (2) and [Ni(phen)3]2[VIV2O2(Hcit)(cit)]Cl·17H2O (3) (H2lact = lactic acid, H3mal = malic acid, H4cit = citric acid, and phen = 1,10-phenanthroline) have been obtained with large counter cation [Ni(phen)3]2+. In mononuclear complex 2, vanadium atom exists in a distorted octahedral environment. The distance of V–O bond (α-alkoxy) in 2 is significantly shorter than V–O bond (α-hydroxy) in [VO(Hmal)(bpy)]·H2O and [VO(Hcit)(phen)]2·6.5H2O [1] reported, which is attributed to the deprotonation of α-alkoxy group in 2. The anions of 1 and 3 have VV2O4 and VIV2O2 diagonal structures respectively and have two bridging oxygen atoms from the alkoxy groups of α-hydroxycarboxylates. The vanadium atoms in 1 and 3 are penta-coordinated, except V1 in 3 is hexa-coordinated. The different coordination modes of carboxy group result in different V–O (α-carboxy) distances.

Microwave and conventional synthesis of ester based dicationic pyridinium ionic liquids carrying hydrazone linkage: DNA binding, anticancer and docking studies

Novel task dicationic ionic liquids (Ts-DiILs) 6–29 were designed and synthesized, under both conventional and microwave conditions; through molecular hybridization of the appropriate bispyridines having a hydrazone linkage as spacer with some alkyl functionalized esters forming the counter cations. Beside the synthesized halogenated DiILs 6–11, fluorinated metal anions were introduced via metathesis reaction in order to create new dipyridinium ionic liquid-hydrazone hybrids 12–29. All newly synthesized DiILs were fully characterized using different spectroscopic tools such as 1H, 13C, 19F, 31P, 11B NMR and Mass experiment. The DNA binding, anticancer and docking studies of the synthesized ionic liquids were also carried out. The DNA binding constants ranged from 4.5 × 104 to 7.2 × 104 M−1, indicating good DNA binding tendencies. The most active ionic liquids were 28 and 29 with 99.99 and 99.86% anticancer activities, respectively. The docking studies indicated DNA binding in the outer grooves of DNA. The reported ionic liquids may be used as future anticancer drugs.

Clean-activation of the B–H bond in closo-decahydrodecaborate [B10H10]2− anion via soft-route

Series of closo-decaborate (NH4)2[B10H10] derivatives were prepared by their direct reaction with ligand L (alcohols or nitriles) via an auto-catalyzed reaction with NH4+ present as a counter cation. The reactions were carried out under mild conditions in open air at reflux in the absence of any subsidiary catalyst. The yield and degree of substitution of the derivatives depend on the duration of the reaction and the applied temperature. Derivatives were characterized by NMR, MS-ESI and TLC. The study elaborates the proposed mechanism of the nucleophilic substitution on [B10H10]2– by illustrating the assistance of an initiator to catalyze the reaction.

Effect of Counter Cations on the Hydrothermal Conversion of FAU-Type Zeolites into ABW or ANA and Their Potential Applicability for CO<sub>2</sub>/N<sub>2</sub> Separation

Effect of Counter Cations on the Hydrothermal Conversion of FAU-Type Zeolites into ABW or ANA and Their Potential Applicability for CO<sub>2</sub>/N<sub>2</sub> Separation

Tunable Adhesion from Stoichiometry-Controlled and Sequence-Defined Supramolecular Polymers Emerges Hierarchically from Cyanostar-Stabilized Anion-Anion Linkages.

Sequence-controlled supramolecular polymers offer new design paradigms for generating stimuli-responsive macromolecules with enhanced functionalities. The dynamic character of supramolecular links present challenges to sequence definition in extended supramolecular macromolecules, and design principles remain nascent. Here, we demonstrate the first example of using stoichiometry-control to specify the monomer sequence in a linear supramolecular polymer by synthesizing both a homopolymer and an alternating copolymer from the same glycol-substituted cyanostar macrocycle and phenylene-linked diphosphate monomers. A 2:1 stoichiometry between macrocycle and diphosphate produces a supramolecular homopolymer of general formula (A)n comprised of repeating units of cyanostar-stabilized phosphate-phosphate dimers. Using a 1:1 stoichiometry, an alternating (AB)n structure is produced with half the phosphate dimers now stabilized by the additional counter cations that emerge hierarchically after forming the stronger cyanostar-stabilized phosphate dimers. These new polymer materials and binding motifs are sufficient to bear normal and shear stress to promote significant and tunable adhesive properties. The homopolymer (A)n, consisting of cyanostar-stabilized anti-electrostatic linkages, shows adhesion strength comparable to commercial superglue formulations based on polycyanoacrylate but is thermally reversible. Unexpectedly, and despite including traditional ionic linkages, the alternating copolymer (AB)n shows weaker adhesion strength more similar to commercial white glue based on poly(vinyl acetate). Thus, the adhesion properties can be tuned over a wide range by simply controlling the stoichiometric ratio of monomers. This study offers new insight into supramolecular polymers composed of custom-designed anion and receptor monomers and demonstrates the utility of emerging functional materials based on anion-anion linkages.

Formation of monomeric Sn(ii) and Sn(iv) perfluoropinacolate complexes and their characterization by 119Sn Mössbauer and 119Sn NMR spectroscopies.

The synthesis and characterization of a series of Sn(ii) and Sn(iv) complexes supported by the highly electron-withdrawing dianionic perfluoropinacolate (pinF) ligand are reported herein. Three analogs of [SnIV(pinF)3]2- with NEt3H+ (1), K+ (2), and {K(18C6)}+ (3) counter cations and two analogs of [SnII(pinF)2]2- with K+ (4) and {K(15C5)2}+ (5) counter cations were prepared and characterized by standard analytical methods, single-crystal X-ray diffraction, and 119Sn Mössbauer and NMR spectroscopies. The six-coordinate SnIV(pinF) complexes display 119Sn NMR resonances and 119Sn Mössbauer spectra similar to SnO2 (cassiterite). In contrast, the four-coordinate SnII(pinF) complexes, featuring a stereochemically-active lone pair, possess low 119Sn NMR chemical shifts and relatively high quadrupolar splitting. Furthermore, the Sn(ii) complexes are unreactive towards both Lewis bases (pyridine, NEt3) and acids (BX3, Et3NH+). Calculations confirm that the Sn(ii) lone pair is localized within the 5s orbital and reveal that the Sn 5px LUMO is energetically inaccessible, which effectively abates reactivity.

Nickel salt of phosphomolybdic acid as a bi-functional homogeneous recyclable catalyst for base free transformation of aldehyde into ester.

A Ni salt of phosphomolybdic acid (NiHPMA) was synthesized and characterized by various physico-chemical techniques such as EDX, UV-Visible spectroscopy, FT-IR, Raman spectroscopy and XPS. FT-IR and Raman spectroscopy confirm the presence of Ni as a counter cation while UV-Visible and XPS studies to confirm the presence of Ni(ii) in the catalyst. The catalyst was evaluated for its bi-functional activity towards the tandem conversion of benzaldehyde to ethyl benzoate and it was found that very small amounts of Ni (2.64 × 10−3 mmol) enhance the selectivity towards benzoate. A detailed mechanistic study was carried out by UV-Visible and Raman spectroscopy to confirm that both intermediate species, Mo–peroxo and Ni–oxo, are responsible for higher selectivity towards esters. Further, a study to determine the effect of addenda atoms (heteropoly acid) was also carried out. The catalyst was also found to be viable for a number of aldehydes under optimized conditions.

Manifold of self-assembly of a de novo designed peptide: amyloid fibrils, peptide bundles, and fractals.

We report that a peptide with the sequence of EGAGAAAAGAGE can have different aggregation states, viz., amyloid fibrils, peptide bundles, and fractal assembly under different incubation conditions. The chemical state of the Glu residue played a pivotal regulating role in the aggregation behavior of the peptide. The mechanism of the fractal assembly of this peptide has been unraveled as follows. The peptide fragments adopting the beta-sheet conformation are well dispersed in alkaline solution. In the buffer of sodium bicarbonate, peptide rods are formed with considerable structural rigidity at the C- and N-termini. The peptide rods undergo random trajectory in the solution and form a fractal pattern on a two-dimensional surface via the diffusion-limited aggregation process.

Intrinsically porous molecular building blocks for metal organic frameworks tailored by the bridging effect of counter cations

Intrinsically porous molecular building blocks are used for the rational design and construction of molecular-level controlled porous materials.

A new 22-Ni-substitued polyoxometalate: Hydrothermal synthesis, structure and electrochemical property

A new inorganic–organic hybrid 22-Ni-substituted phosphotungstate, [Ni(H2O)2(en)]2[Ni(H2O)(en)2]2{[Ni6(OH)2(H2O)(en)2(B-α-PW9O34)]2[W4O16][Ni5(H2O)3(en)3(PW6O26)]2}·24H2O (1, en = ethylenediamine) has been made by hydrothermal method and characterized by elemental analysis, single crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis, and UV–Vis diffuse-reflectance spectroscopy, respectively. Compound 1 contains a 22-Ni-substituted polyoxoanion built by central [W4O16]8− core and two different symmetrical clusters, [Ni6(OH)2(H2O)(en)2(B-α-PW9O34)]+ and [Ni5(H2O)3(en)3(PW6O26)]−, which is further linked by double-bridging [Ni(H2O)2(en)]2+ cations to form 1-D chain. Moreover, the counter cations, [Ni(H2O)(en)2]2+ support to the [B-α-PW9O34]9− fragments.

Solvent-assisted monomeric molecular structure of the phosphate diester and the synthesis of menthol-based phosphate diesters

Phosphate diesters are well known to form intermolecular H-bonded dimeric structures in their solid-state. Recently, we reported 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester exists as H-bonded monomeric molecular structure along with water dimer in the solid-state. Herein we report 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me2NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties. We also used the alcohols, ROH (R = Me, Et, iPr, and tBu), for crystallisation of 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester. In these instances, solvent-incorporated dimeric structures are found in the solid-state. We also report the syntheses and molecular structures of anionic phosphate diesters of 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester possessing various counter cations. Moreover, we also report the syntheses and molecular structures of phosphate diesters based on (−)-menthol, (+)-menthol and (+)/(−)-menthol. These exist as H-bonded dimers in the solid-state. Herein we report 2,6-(CHPh)2-4-iPr-phenyl substituted phosphate diester forms a monomeric molecular structure in the solid-state upon co-crystallization with dimethylformamide, DMF (Me2NCHO). The -CHO group of DMF simultaneously acts as an H-bond acceptor to P-OH and an H-bond donor to P=O moieties.

Designing Functional Polyoxometalate‐Based Ionic Liquid Crystals and Ionic Liquids

Polyoxometalate (POM) compounds constitute a wide family rich of more than several thousand inorganic compounds which can be finely tuned at the molecular level. Considering the high diversity in their structures and properties, the incorporation of such inorganic components into liquid crystalline phases or ionic liquid phases is particularly relevant for the elaboration of functional materials. By adjusting the molecular structures of the anions and the nature of the counter cations, many authors designed different types of mesophases sometimes with application in optoelectronics, or true POM‐based ionic liquids (POM‐ILs with melting temperatures below 100 °C). The latter turn out to be highly interesting for various applications in catalysis, depollution, or protection of the historical heritage. This review focuses on the recent developments in these organic/inorganic hybrid materials, POM‐based ionic liquid crystals and POM‐ILs, and their applications.

Synthesis, structures, thermal and magnetic properties of two bis(oxalato)cuprate(II) hybrid salts containing pyridinium derivative cations

Two bis(oxalato)cuprate(II) hybrid salts, (C 5 H 7 N 2 ) 2 [Cu(C 2 O 4 ) 2 ]·2H 2 O ( 1 ) and (C 7 H 11 N 2 ) 2 [Cu(C 2 O 4 ) 2 ]·5H 2 O ( 2 ) (C 5 H 7 N 2 = 3-aminopyridinium; C 7 H 11 N 2 = 2-amino-4,6-dimethylpyridinium) have been synthesized and characterized by elemental and TGA-DSC analyses, IR and UV–Vis, single-crystal X-ray diffraction and magnetic susceptibility measurements. The polymeric anionic motifs in the two salts are significantly different. In 1 , stacking of [Cu(C 2 O 4 ) 2 ] 2- units through axial Cu⋯O contacts (2.890 Å) yields straight Cu(II) chains, with a prolate CuO6 octahedron around Cu(II) ions, formed by two cis -chelated oxalate anions and two axial O-atoms of neighboring [Cu(C 2 O 4 ) 2 ] 2- units. By contrast, in 2 , stacking of [Cu(C 2 O 4 ) 2 ] 2- units occurs via bis-bidentate oxalate groups, yielding zigzag Cu(II) chains with a distorted CuO6 coordination sphere. Thermal studies confirmed the presence of solvent water molecules in both salts. Magnetic studies revealed weak antiferromagnetic and weak ferromagnetic interactions between Cu(II) ions in 1 and 2 , respectively. The synthesis of two hybrid salts containing bis(oxalato)cuprate(II) units and pyridinium derivatives as counter cations is presented. The solid state structures of these salts highlight different coordination modes of oxalate ligand, leading to straight and zigzag Cu(II) chains for compounds 1 and 2 , respectively. 1 exhibits weak antiferromagnetic interactions whereas 2 exhibits weak ferromagnetic interactions. • Two hybrid salts (C 5 H 7 N 2 ) 2 [Cu(C 2 O 4 ) 2 ]∙2H 2 O ( 1 ) and (C 7 H 11 N 2 ) 2 [CuC 2 O 4 ) 2 ]·5H 2 O ( 2 ) have been synthesized. • Compounds 1 and 2 crystallize in the monoclinic system, space group P 2 1 /c and in triclinic system, space group P -1, respectively. • Hydrogen bonding interactions occur between cations, anions and solvent waters. • Different coordination modes of oxalate ligand are observed in the two (oxalato)cuprate(II) hybrid salts. • Compounds 1 and 2 exhibit weak antiferromagnetic and weak ferromagnetic interactions, respectively.

Optical properties of two bismuth(III) halide hybrids with pyridyl sulfide derivative counter cations

Low dimensional organic-inorganic hybrid Bi(III) halides, especially those containing organic N, S-heterocycles are amazing as solid state photoluminescent materials, but remain less explored. Herein, two bismuth(III) halide compounds, (Etmp)4Bi2X10 (X = Cl for 1, Br for 2, Etmp = 4-(ethylthio)pyridin-1-ium), are obtained by employing pyridyl sulfide derivative as counter cations. They are determined as zero-dimensional (0D) ionic structures, featuring binuclear bismuth halide anions charge-compensated by (Etmp)+ counter cations. Solid-state UV–Vis diffuse reflectance spectra reveal the wide optical band gaps of 3.20 eV for 1 and 2.67 eV for 2. Notably, 1 exhibits a strong green photoluminescence emission with a quantum yield of 20%, and a CIE chromaticity coordinate of (0.27, 0.36) when irradiated by a 394-nm light. Theoretical calculations suggest that the charge transition between Cl-3p and p-π* anti-bonding orbital of (Etmp)+ is responsible for the emission.

Synthesis of N-Alkyl and N-H-Carbazoles through SN Ar-Based Aminations of Dibenzothiophene Dioxides.

Alkyl amines have become available for the synthesis of diverse N-alkyl carbazoles through twofold SN Ar aminations of dibenzothiophene dioxides by using alkali metal bases. Of particular importance is the choice of counter cations on alkali metal bases, that is, i) the use of Li base for the efficient intermolecular reaction and ii) the sequential addition of heavier alkali metal bases (Na, K, or Cs) to promote intramolecular cyclization in a one-pot manner. This protocol also enables the cascade synthesis of N-H-carbazoles by using 2-phenylethylamine by removal of the 2-phenethyl group from N-(2-phenethyl) carbazoles in a single operation.

Direct Solution-Based Synthesis of Na4 (B12 H12 )(B10 H10 ) Solid Electrolyte.

All-solid-state batteries (ASSBs) promise higher power and energy density than batteries based on liquid electrolytes. Recently, a stable 3 V ASSB based on the super ionic conductor (1 mS cm-1 near room temperature) Na4 (B12 H12 )(B10 H10 ) has demonstrated excellent cycling stability. This study concerns the development of a five-step, scalable, and solution-based synthesis of Na4 (B12 H12 )(B10 H10 ). The use of a wet chemistry approach allows solution processing with high throughput and addresses the main drawbacks for this technology, specifically, the limited electrode-electrolyte contact and high cost. Moreover, a cost-efficient synthesis of the expensive precursors Na2 B10 H10 and Na2 B12 H12 is also achieved through the same process. The mechanism of the reactions is investigated and two key parameters to tune the kinetics and selectivity are highlighted: the choice of counter cation (tetraethylammonium) and solvent.

Separation and Preconcentration of Trace Uranium(VI) by Solid Phase Extraction with 2,3-Dihydroxynaphthalene and Cetyltrimethylammonium Bromide on Molten Naphthalene and Its LED Fluorimetric Determination in Water Samples.

A simple and rapid solid phase extraction (SPE) procedure has been developed for the extraction and determination of uranium in water samples. The method is based upon the adsorption of uranium(VI)-2,3-dihydroxynaphthalene complex on microcrystalline naphthalene at the pH range 10 - 12 in the presence of a counter cation cetyltrimethylammonium ion. The solid mass consisting of uranium-2,3-dihydroxynaphthalene-CTA complex and naphthalene is ignited in the furnace at a temperature of 700°C for 1 h and then digested in dil. HNO3 solution. Uranium is then determined by LED fluorimetry using fluorescence enhancing pyrophosphate buffer. The effects of different variables like pH of the solution, reagent concentrations, counter cations, stirring time, interfering ions etc. have been investigated thoroughly for the quantitative recovery of uranium. The accuracy of the developed method has been ascertained by standard addition method as well as conventional pellet fluorimetry method involving co-precipitation of uranium using aluminum phosphate as a carrier.

Effect of Sodium Ions on Catalytic Performance of TS-1 in Gas-Phase Epoxidation of Propylene with Hydrogen Peroxide Vapor

Na+ ions in TS-1 influence the results of liquid-phase oxidations of hydrocarbons seriously, and the avoiding of Na+ ion impurity in TS-1 synthesis is crucial for its catalytic application. In this paper, however, the solvent-free gas-phase epoxidation of propylene with H2O2 vapor (G-HPPO) was investigated over TS-1 zeolites with different Na+ ion content. Significant improvement in the performance of G-HPPO process was observed with NaOH solution hydrothermally modified TS-1 which had a Na/Ti ratio of 0.68. The performance of G-HPPO process was further enhanced when the Na/Ti ratio of hydrothermally modified TS-1 was increased to 1.0 via subsequent Na+ ion impregnation. The catalyst showed 16.9% propylene conversion, 97.5% PO selectivity and 79.3% H2O2 utility at a propylene to H2O2 ratio of around 5. On the other hand, when the Na+ ion content of the hydrothermally modified TS-1 was reduced via subsequent NH4+-exchange, the resulted catalyst exhibited a remarkably deteriorated G-HPPO process performance. By Combining the characterizations of UV–Raman, UV–vis and FT-IR with DFT calculation, it is concluded that in the NaOH solution hydrothermally modified TS-1 the Na+ ions served as counter cations of the silicon hydroxyls adjacent to “open” tetra-coordinated framework Ti sites. As a result, the local environment of the “open” Ti sites (with titanium hydroxyls) was adjusted and the Ti sites were properly activated. Whereas, in the case of excess Na+ ions were introduced into the TS-1 (for example Na/Ti ratio more than 1.0), the titanium hydroxyl of the “open” Ti sites would be occupied, to which the deteriorated G-HPPO process performance was ascribed.

Charge-neutral and self-doped cyclopentadithiophene-based conjugated polymers: Influence of side chain on optical, electrical, and thermoelectric properties

Water-soluble cyclopentadithiophene-based conjugated polymers (CP1–Na, CP2–Na, and CP3–Na) having the sodium propanesulfonate side group and with different comonomer units were synthesized by Suzuki-Miyaura polymerization under the microwave heating at 90 °C for 8 h. Number-averaged molecular weights determined by GPC analyses after exchanging the counter cation ranged from 6200 to 10400. TGA measurements revealed that the degradation temperatures at 10% weight loss of polymers exceed 250 °C. UV–vis–NIR spectra exhibited broad absorptions at 950–1000 nm originated from the polaronic band, in which the intensity of this band was largest for CP3–Na with the bis(methylsulfanyl)methylene unit. The spin density calculated from EPR spectra was largest for CP2–Na with triethylene glycol chains (6.4 × 1016 for 1 mg). The electrical conductivity, Seebeck coefficient, and power factor of CP3–Na were estimated as 9.1 × 10−3 S cm−1, 34 μV K−1, and 1.1 × 10−3 μW m−1 K−2, respectively.