Cations In Aqueous Solution Research Articles

Modular Assembly of Isostructural Mixed-Ligand Uranyl Coordination Polymers Based on a Patterning Strategy.

Controlling the orderly assembly of molecular building blocks for the formation of the desired architectural, chemical, and physical properties of the resulting solid-state materials remains a long-term goal and deserves to be examined. In this work, we propose a patterning strategy for modular assembly and structural regulation of mixed-ligand uranyl coordination polymers (CPs) through the combination of couples of organic ligands with complementary molecular geometry and well-matched coordination modes. By using a 5-(p-tolyldiazenyl)isophthalic acid ligand (H2ptdi) with different rigid linear bicarboxylic acid linkers to construct a well-defined ladder-like pattern, five novel isostructural uranyl coordination polymers, [(UO)2(ptdi)(bdc)0.5](dma) (1), [(UO)2(ptdi)(bpdc)0.5](dma) (2), [(UO)2(ptdi)(tpdc)0.5](dma) (3), [(UO)2(ptdi)(ndc)0.5](dma) (4), and [(UO)2(ptdi) (pdc)0.5](dma) (5) {H2bdc, 1,4-dicarboxybenzene; H2bpdc, 4,4'-biphenyldicarboxylic acid; H2tpdc, terphenyl-4,4″-dicarboxylic acid; H2ndc, 2,6-naphthalenedicarboxylic acid; H2pdc, 1,6-pyrenedicarboxylic acid; [dma]+, [(CH3)2NH2]+}, were successfully synthesized. Structural analysis reveals that 1-5 have similar ladder-like units but different sizes of one-dimensional nanochannels and interlayer spacing due to the different lengths and widths of the linkers. Because of the changes in interlayer spacing of these isostructural cationic frameworks, differences in the performance of Eu3+ ion exchange with [dma]+ are observed. Moreover, those compounds with high phase purity have been further characterized by thermogravimetric analysis, infrared spectroscopy, and luminescence spectroscopy, element analysis, PXRD and UV spectroscopy. Among them, compound 3 with strong fluorescence can selectively detect Fe3+ over several competing metal cations in aqueous solution. This work not only provides a feasible patterning method for effectively regulating the modular synthesis of functional coordination polymers but also enriches the library of uranyl-based coordination polymers with intriguing structures and functionality.

Kinetically-controlled formation of Fe2O3 nanoshells and its potential in Lithium-ion batteries

• A wet chemical synthetic protocol was developed to build uniform Fe 2 O 3 nanoshells. • Hexamethylenetetramine was critical in modulating the precipitation kinetics. • This protocol was successful in building Fe 2 O 3 coatings around various substrates. • A nondestructive surface treatment could be achieved by this anhydrous protocol. • The cycling performance of LiNi 0.5 Mn 1.5 O 4 greatly improved after Fe 2 O 3 coating. The construction of uniform metal oxide nanoshells has been widely considered as an effective protocol for the protection of high energy cathodes in lithium-ion batteries. Solution-based synthetic routes have recently become feasible to build such protective shells, but are challenged by the incidental damage to cathodes since an acidic condition is usually needed to prevent the fast precipitation of active metal cations in aqueous solutions. Here, by switching to anhydrous solution, we demonstrate the possibility of creating Fe 2 O 3 nanoshells by taking advantage of the much-reduced ionic activity of Fe 3+ in ethanol without the involvement of corrosive environment. Hexamethylenetetramine is identified as an efficient growth controller, whose slow decomposition is critical to modulate the growth kinetics of the formed metal hydroxide precursor, forming core@shell structures with the shell thickness controlled at nanometer accuracy. This synthetic protocol is successful in building uniform Fe 2 O 3 coatings around various substrates, particularly LiNi 0.5 Mn 1.5 O 4 , a well-known high energy cathode whose applications are challenged by poor cycling performance related to the high working voltage. This surface treatment for LiNi 0.5 Mn 1.5 O 4 is effective in improving the electrochemical behavior of the cathode with a successful suppression of its structural degradation as well as a substantial improvement in its high temperature stability.

A new tool for disinfecting household drinking water for rural residents: protonated mordenite-embedded sheet

Abstract Many rural residents in developing countries drink water contaminated with feces due to inadequate purification, causing many diarrheal deaths, most of them infants. We have fabricated a protonated (H+-retaining) mordenite-embedded non-woven fabric sheet (H-MES) as a new tool for disinfecting drinking water at home. Proton retention amount was 1.2 mmol per gram of mordenite, 75% of its cation-exchange capacity. The H-MES released protons through cation exchange with cations in aqueous solutions, lowering the pH of the solutions to below 4. This low pH led to disinfecting 100 mL of 100-fold diluted TSB solutions containing an Escherichia coli species (DH5α). For example, an initial viable count of around 5,000 CFU mL−1 decreased to 14 CFU mL−1 after 24 h shaking at 25 °C with added H-MES containing 0.2 g protonated mordenite; 3.8×107 CFU mL−1 without the H-MES. Adding a nitric acid solution showed a similar effect, but using chemical reagents at home might lead to unexpected accidents. Adding and removing the H-MES to and from household waterpots by hand is easy. Besides the H-MES, similar sheets embedded with bactericides and bacterial adsorbents could be a simple water-disinfection tool for rural residents.

Interaction of functionalised surfaces on silica with dissolved metal cations in aqueous solutions

Abstract The study clearly shows that different metal cations were efficiently removed from water by employing coated silica particles with SO3H-terminated functionalized surfaces. Significant amounts of Fe, Mn, Ca, Mg, Na, and K could be removed from natural water samples with different concentrations varying from 0.075 mg/l for Mn up to 12 000 mg/l for Na by stirring the functionalized silica particles in the water samples for 1 h at room temperature. ICP–MS verify the removal of the elements and ToF-SIMS analyses clearly showed the presence of the elements on the particles after the treatment procedure. The removal of the metal cations is believed to be due to electrostatic attraction of the positively charged presumably hydrolysed metal cations to the negatively charged deprotonated SO3H-groups. However, from the current study it can not be excluded that chemisorption of the cations by the SO3H-group may be possible.

Viologen‐Based Uranyl Coordination Polymers: Anion‐Induced Structural Diversity and the Potential as a Fluorescent Probe

AbstractFour novel uranyl coordination polymers (CPs) have been synthesized by the utilization of viologen derivative ligand, 1,1’‐bis(3,5‐dicarboxyphenyl)‐4,4’‐bipyridinium (H4bdbp ⋅ 2Cl), and uranyl nitrate under hydrothermal reactions through the regulation of different kinds of inorganic acids (HF, HCl, HNO3, HClO4, H2SO4). Compound 1 features a unique triple‐stranded helix structure with a helical pitch of 31.578 Å. The ligands in compounds 2–4 have similar configurations, while their 3D structures are completely different due to the presence of different kinds of anions. The anions play different roles in the frameworks of these uranyl CPs. In addition, compound 2 possesses strong fluorescence both in solid‐state and aqueous suspension‐state. It is demonstrated that compound 2 can selectively detect Fe3+ over several competing metal cations in aqueous solution.

A new fluorescence probe for simultaneous determination of Fe2+ and Fe3+ by orthogonal signal correction-principal component regression

In this research, a newly reported fluorescence molecular probe [N, N’-bis(methylsalicylaldehyde)-4,4 bipyridinium] dichloride (DALD) was used for selective detection and determination of Fe2+ and Fe3+ in aqueous solutions. The complexation reaction between DALD and Fe2+ and Fe3+ is the basis of the variation in the emission intensity and their quantitative fluorescence determination. The stoichiometries and formation constants of DALD and both ions were obtained by appropriate chemical model and numerical refinement of spectrofluorometric-mole ratio titration data. The selectivity of the probe towards Fe2+ and Fe3+ was tested in the presence of Mn+ (n = 1, 2, 3) cations. None of the other ions show any observable fluorescence signal quenching at the excitation and emission wavelengths (345/456 nm). The emission profile of said iron species was in the range of 340–560 nm and has shown a high degree of overlap. The univariate calibration ranges and detection limits of Fe2+ and Fe3+ were 0.7–4.1 μM, 0.7–2.7 μM and 1.3 μM, and 0.69 μM, respectively. The orthogonal signal correction-principal component regression (OSC-PCR) as a factor-based and data compression method was used to determine both cations in aqueous solutions simultaneously. OSC-PCR correlates the fluorescence spectra to the concentration of metal ions very well, and the coefficients of determination were 0.9530 and 0.9919 for Fe2+ and Fe3+, respectively. The solution equilibria of interaction between the probe and metal ions were studied and the stability constants of complexes were 10.68 (± 0.05), 1:2 and 4.46 (± 0.12) 1:1 for Fe2+ and Fe3+ respectively. The factors that influenced sensitivity and selectivity were recognized and optimized.

Fluorimetric detection of Ag+ cations in aqueous solutions using a polyvinyl chloride sensor film doped with crown-containing 1,8-naphthalimide

A composite material based on polyvinyl chloride and a 1,8-naphthalimide derivative containing an azadithia-15‑crown-5 ether receptor showed a fluorescent response to silver cations in an aqueous solution at low concentrations.

Synthesis, structure and fluorescence property of a new Zn-MOF based on a tetraphenylethane (TPE) ligand

A new 3D luminescent Zinc (II) metal-organic framework, has been solvothermally synthesized by using Zn(NO3)2⋅4H2O and a mixture of ligands: Titpe ligand and bcpf ligand. The molecular formula is [Zn(Titpe)(bcpf)•(DMF)]n, (Compound 1, Titpe = 1,1,2,2-tetrakis(4-(1H-imidazol-1-yl)phenyl)ethane, bcpf= 4,4΄-sulfonyldibenzoic acid). Compound 1 crystallizes in the triclinic system, space group P -1, with a=12.9990(9), b=14.2181(10), c=14.3781(10) Å, α = 89.974(4)°, β = 71.640(4)°, γ = 80.732(4)°, V = 2485.6(3) Å3, Z = 2, Mr = 1039.43, Dc =1.389 g/cm3, μ = 0.600 mm−1, F(000) = 1076.0, R = 0.0747 and wR =0.2508 for 9724 observed reflections (I > 2σ(I)). Topology analysis shows that compound 1 is a double interpenetrating structure. In addition, due to the ligand-to-ligand charge transfer of the TPE chromophore, luminescent spectra of 1 shows that it emits strong blue light. Compound 1 can detect Fe3+ ions with high selectivity and sensitivity among diverse inorganic cations in aqueous solution and is also a highly selective sensing material for CrO42− and Cr2O72- ions.

Temperature-Triggered Structural Dynamics of Non-Coordinating Guest Moieties in a Fluorescent Actinide Polyrotaxane Framework.

We present here the synthesis of a novel fluorescent actinide polyrotaxane compound URCP1 through the utilization of an end-cutting pseudorotaxane precursor with only the cucurbit[6]uril (CB[6]) macrocyclic components acting as linking struts. The non-coordinating guest motif in the obtained polyrotaxane, with increased freedom and structural flexibility, can display intriguing temperature-triggered conformational variations inside the cavity of CB[6], which was clearly evidenced by crystallographic snapshots at different temperatures. Notably, this observation of temperature-triggered structural dynamics in URCP1 represents the first report of actinide polyrotaxane with such feature in solid-state. Moreover, URCP1 has a high photoluminescence quantum yield (PLQY) of 49.8 %, comparable to other luminescent uranyl compounds, and can work as a fluorescent probe to selectively detect Fe3+ over other eight competing cations in aqueous solution, with the limit of detection being as low as 4.4×10-3 ppm.

Quantifying the influence of divalent cations mass transport on critical flux and organic fouling mechanism of forward osmosis membrane

Understanding the insightful impact of divalent cations mass transport on the complex organic fouling of forward osmosis (FO) membrane is vital when seawater/brine is utilized in a FO hybrid process. Our works deeply focused on quantifying the influence of divalent cations on not only critical flux but also the organic fouling mechanism. The presence of divalent cations in aqueous solutions caused a decrease in critical flux values. The fouling mechanism is mainly governed by intermolecular and ion-mediated interactions. The findings suggested the interaction of divalent cations with organic matters close to the membrane surface is more noticeable than that in the feed solution. These interactions combined with an operation at the flux ≥30 LMH led to the formation of a compact and cohesive cake layer (4.8–9.1 μm) where the great divalent cations were deposited on membrane surface after 30 h operation (Ca2+: 162.13–256.72 g/m2, Mg2+: 182.60–374.38 g/m2). In contrast, 21 LMH below critical value exhibited minor fouling with a very thin cake layer (0.5 μm) and minimized deposited divalent cations (Ca2+: 79.47 g/m2, Mg2+: 46.65 g/m2). Overall, the extended operation of 30 h suggested 16–21 LMH were threshold values for FO fouling control.

Application of modified green algae Nannochloropsis sp. as adsorbent in the simultaneous adsorption of Methylene Blue and Cu(II) cations in solution

Biomass of algae is a very potent adsorbent for absorbing aqueous waste containing heavy metals and organic dyes. This study purposes to confirm the ability of adsorbents from green algae Nannochloropsis sp. modified with silica (ASN) and followed by coating magnetite particles (ASN-MPs) to absorb simultaneously the mixture of Methylene Blue (ME) and Cu(II) cations in aqueous solution. Simultaneous sorption of ME and Cu(II) cations to ASN and ASN-MPs was carried out by the batch method with the interaction pH condition 7, contact time 90 min, and initial concentrations of ME and Cu(II) cations (0.1–1.0 mM). Based on adsorption data, Cu(II) cations have a greater adsorption rate and capacity (qm) compared to ME at the same contact time and initial concentration. The adsorption capacity (qm) values of the bi-component ME and Cu(II) cation mixture in ASN and ASN-MPs were 1.39 × 10− 1 and 5.32 × 10− 1 mmol g− 1, respectively, with the binary Langmuir adsorption isotherm constant for Cu(II) cations greater than ME. Modified adsorbent from algae Nannochloropsis sp. with silica matrix and magnetite particle coating is an adsorbent that has a high effectiveness in the collective sorption of ME and Cu(II) cations. Therefore, these adsorbents can be used for the adsorption of cation mixtures of heavy metals and organic dyes that are cationic in solution.

Accessory ligand strategies for hexacyanometallate networks deriving perovskite polycrystalline electromagnetic absorbents

The controllable adjustment of electromagnetic (EM) properties for high-efficiency EM absorbents are indispensable, nonetheless, rare in crystals engineering regulation. Herein, for the first time, regulated amount of sodium citrate was employed as accessory ligand of cobalt cation in aqueous solution to kinetically assist the controllable fabrication of Prussian blue analogs (PBAs) and corresponding lanthanide perovskite hybrid CoFe alloy polycrystals. Especially, the multi-phase features were analyzed based on Rietveld refinement of XRD patterns, illustrating the existence of distortions, defects and heterogeneous interfaces in resultant polycrystals. Benefited to the dielectric and magnetic adjustment, polycrystalline absorbents achieved excellent impedance matching and EM attenuation, as the minimum reflection loss of CoFe/LaFeO3 and CoFe/LaFeO3/La2O3 reached -44.13 and -33.95 dB, ranking broadest effective bands up to 4.88 and 3.36 GHz. The validity of the strategy provided a novel sight into the controllable fabrication of high-performance magnetic semiconductor polycrystalline devices.

Recent progresses in luminescent metal-organic frameworks (LMOFs) as sensors for the detection of anions and cations in aqueous solution.

The discharge of excessive metal ions and anions into water bodies leads to the serious pollution of water and environment, which in turn has a certain impact on industry, agriculture, and human life. Because of the unique advantages of luminescent metal-organic frameworks (LMOFs), they have been successfully explored as various fluorescent probes to quickly and effectively detect these pollutants. This perspective not only introduces the design strategy and classification of LMOFs, especially the construction methods of water-stable LMOFs, but also reports the latest progresses in some LMOFs between 2016 and 2020 as well as expounds the mechanisms of LMOFs for detecting anions and cations. Moreover, the luminescence properties of LMOFs are related to the selection of metal ions, the structure of organic ligands, the pore size, and the interaction of guest molecules. Finally, the further development of LMOFs is summarized and prospected in this field.

A quinoline-based fluorescent chemosensor for palladium ion (Pd2+)-selective detection in aqueous solution

Quinoline-based fluorescent chemosensors have been extensively developed for various metal cations, but it was still rare for Pd2+-selective detection. In this work, a novel quinoline-benzimidazole conjugate containing one carboxylic acid group (QBM) was designed, and the QBM displayed highly selective fluorescence quenching response towards Pd2+ over other metal cations in aqueous solution. The fluorescence titration revealed a good linear relationship between the fluorescence intensity and the Pd2+ concentration in the range of 0.5–10 μmol L−1, with the detection limit of 0.26 μmol L−1 (S/N = 3). Fluorescence detection of Pd2+ in practical water sample was also successfully achieved.

Study on behavior of lithium ion in solvent extraction and isotope separation

Current research found that the extraction process of lithium ions by crown ether-ionic liquid system was a cation exchange process in which lithium ions are dehydrated. Obtained and predicted the structure of the composite product of crown ether and organolithium, and based on the weighing method, the formation of 1:1 complex [Li(B15C5)]+ was determined. and it was found that the extraction of lithium ion by the diluent was in accordance with the cavity effect of anion. The coextraction of diluent and ionic liquid, the percentage of competition of common metal cations in aqueous solution to the extraction of lithium ions by Benzo-15-crown 5-Ether(B15C5) were also discussed. Finally, the effect of different diluents on lithium isotope separation and the thermodynamics of lithium isotope exchange in the B15C5-[HMIm][NTf2]-anisole system were studied. The separation factor of lithium isotope was the largest when chloroform was used as the diluent (α = 1.034), and the exchange of lithium isotopes was a spontaneous reaction at low temperature (ΔH < 0, ΔS < 0).

Differential Photosensor Activities for the L-Cysteine and L-Serine Capped ZnS:Mn Nanocrystals in the Detection of Divalent Transition Metal Ions in Aqueous Solution.

Colloidal ZnS:Mn nanocrystals (NCs) were synthesized in water by capping the NC surface with conventional amino acids: L-cysteine (Cys) and L-serine (Ser) molecules, which have very similar structures but different terminal functional groups. The optical properties were investigated by using UV-Visible and photoluminescence (PL) spectroscopy. The PL spectra for both ZnS:Mn-Cys and ZnS:Mn-Ser NCs showed broad emission peaks at 590 nm. The measured average particle size from the high-resolution transmission electron microscopy (HR-TEM) images were 4.38 nm (ZnS:Mn-Cys) and 5.57 nm (ZnS:Mn-Ser), which were also supported by Debye-Scherrer calculations. In addition, the surface charge of the NCs in aqueous solutions were measured using zeta-particle size analyzer spectroscopy, which showed formation of negatively charged surface for the ZnS:Mn-Cys (-43.93 mV) and ZnS:Mn-Ser (-8.21 mV) NCs in water. In this present study those negatively charged NCs were applied as photosensors for the detection of specific divalent transition metal cations in aqueous solution at the same condition. Consequently, the ZnS:Mn-Cys and ZnS:Mn-Ser NCs showed totally different photosensor activities upon the addition of first-row divalent transition metal ions. The former NCs showed luminescence quenching for most added metal ions except for Zn (II) ions; whereas the latter NCs showed exclusive quenching effect for Cu (II) ions at the same conditions. These results suggested that those NCs can be applied as Zn2+ and Cu2+ ion sensors in water.

Synthesis of Hydrazinylpyridines via Nucleophilic Aromatic Substitution and Further Transformation to Bicyclo[2.2.2]octenes Fused with Two N-Aminosuccinimide Moieties

AbstractEfficient and reliable synthesis of substituted hydrazinylpyridines in thick-wall ACE tubes via nucleophilic substitution of a chlorine substituent in different chloropyridines is presented. Hydrazine hydrate and alkylhydrazines were used as nucleophiles and simple alcohols and diethyl ether were the only organic solvents necessary, making the process environmentally and user friendly, potentially reaching 100% atomic efficiency. In the next step, transformations of succinic anhydride moieties fused to the bicyclo[2.2.2]octene framework into succinimide moieties via nucleophilic substitution of oxygens were conducted. As nucleophiles two of the synthesized hydrazinylpyridines (2-hydrazinyl-3-nitropyridine and 2-hydrazinyl-5-nitropyridine) and also hydrazine hydrate, phenylhydrazine, and 4-nitrophenylhydrazine were used. Reactions were again carried out in ACE tubes and only simple alcohols, diethyl ether, and acetone were needed as solvents. One of the prepared bicyclo[2.2.2]octene adducts displayed water solubility thus being a promising candidate for future studies as a novel bidentate ligand for various metal cations in aqueous solutions or acting as an unprecedented halogen bond acceptor.

A simple electrogravimetric experimental setup to determine Cu in alloy samples for teaching purposes

Electrogravimetry is a traditional analytical method for the determination of cations in aqueous solution, but the use of platinum as cathode and anode electrodes hinders its implementation in undergraduate chemistry courses with limited resources. This study proposes the replacement of expensive platinum electrodes by cheaper materials such as the dimensionally stable anode and Ni–Cr alloy as the cathode, which showed good performance in the determination of Cu by electrolysis at constant current (in galvanostatic mode). The proposed method achieved an electrogravimetric yield of 97.3 ± 0.9%, from a solution of CuSO4 during electrolysis carried out at 0.26 A for 60 min. The experimental setup was used to determine Cu in commercial scrap alloy waste samples containing Cu, Sn, Pb, and Zn, following a simple pretreatment employing ammonia solution. The Cu weight percentage obtained was 58.6 ± 0.5%, which was in agreement with a value of 59.4 ± 1.7% obtained using a comparative spectrophotometric method.

TWO 3D Cd (II) luminescent coordination polymers as highly selective and sensitive sensing for Fe3+ and CrO42−/Cr2O72− ions in aqueous system

Two 3D Cd (II) luminescent coordination polymers (LCPs), namely, {[Cd(bimb)Cl2]·1.5H2O}n (1) and {[Cd1.5(bbib)2.5Cl2]·3H2O·NO3}n (2) { bimb ​= ​1,3-Bis (imidazol-1-ylmethyl) benzene, bbib ​= ​1,4-bis (benzoimidazo-1-ly) benzene } have been obtained under solvothermal conditions The structural analysis of LCPs exhibited that they are 3D frameworks with (4,6)-connected dia network for 1 and (4,5)-connected tck topology network for 2. The solid state fluorescence of ligands and LCPs, and luminescent sensing experiments of LCPs for anions and cations in aqueous solutions were systematically studied. Compared with the free bimb and bbib ligands, the emission peaks of 1 and 2 are slightly red-shifted, which can be assigned to the effect of coordination. Furthermore, the fluorescence experiments indicated that LCPs 1 and 2 have high sensing sensitivity and selectivity toward Fe3+ and CrO42−/Cr2O72− ions in water system.

Efficiency of H2O2-treated eucalyptus biochar on the removal of Cu(II), Cd(II) and Ni(II) from aqueous solution

The present work had the goal to produce H2O2-treated biochar from eucalyptus wood and testing its efficiency in the removal of heavy metals from aqueous solutions. Oxidizing treatment was performed by reacting biochar with H2O2 (10% m/m) during 4 hours at pH 8.0 and 80 °C. Fresh and H2O2-treated biochar samples were characterized by thermogravimetry and elemental analysis. Point of zero charge and specific surface area were determined. Adsorption kinetics tests with Cu were carried out and Langmuir and Freundlich isotherms were adjusted. Adsorption tests were conducted with a mixture of Cu, Ni and Cd cations in aqueous solution. The best adsorption capacity was achieved in acid pH. H2O2-treated biochar had adsorption capacity of 170.41 mg&nbsp;L?1 for Cu alone and 305.35&nbsp;mg L?1 for the mixture of metals. Adsorption was best predicted by the Langmuir isotherm (R2 = 0.9976). Despite the significant decrease in the specific surface area, the H2O2-treated biochar showed better performance in the adsorption of heavy metals compared to the original biochar, especially in the presence of more than one metallic cation.