Anion Of Salt Research Articles

Paradoxes and paradigms: on ambisaline ions of nitrogen

Ambisaline ions can be defined as species that exist as cations and as anions in appropriate salts although admittedly not necessarily with well-known or commonly existing counterions. In the present paper we review ambisaline ions of nitrogen as present in solid state salts and add a brief thermochemical commentary. We open our discussion with all nitrogen species composed of solely nitrogen and extend it to polynitrogen ambisaline species consisting of nitrogen(s) with hydrogen (or other univalent groups) affixed to these nitrogens.

Linking of CuI Units by Tetrahedral Mo2 E2 Complexes (E=P, As).

The reaction of [Cp2Mo2(CO)4(μ,η2:2‐E2)] (A: E=P, B: E=As, Cp=C5H5) with the WCA‐containing CuI salts ([Cu(CH3CN)4][Al{OC(CF3)3}4] (CuTEF, C), [Cu(CH3CN)4][BF4] (D) and [Cu(CH3CN)3.5][FAl{OC6F10(C6F5)}3] (CuFAl, E)) affords seven unprecedented coordination compounds. Depending on the E2 ligand complex, the counter anion of the copper salt and the stoichiometry, four dinuclear copper dimers and three trinuclear copper compounds are accessible. The latter complexes reveal first linear Cu3 arrays linked by E2 units (E=P, As) coordinated in an η2:1:1 coordination mode. All compounds were characterized by X‐ray crystallography, NMR and IR spectroscopy, mass spectrometry and elemental analysis. To define the nature of the Cu⋅⋅⋅Cu⋅⋅⋅Cu interactions, DFT calculations were performed.

The influence of varying reaction conditions on the coordination behavior of the phosphonoformate anion

In medical and pharmaceutical science phosphonic acids and phosphonates play an important role with regard to their wide application in various drugs as medicines against osteoporosis or antiviral agents. In the course of the investigations on the coordination chemistry of biologically active phosphonates different salts of the phosphonoformate anion were prepared via hydrolysis of corresponding esters under basic conditions. Depending on the reaction and crystallization conditions, different sodium salts with the phosphonoformate moiety were obtained and structurally characterized.

Extraction and separation of lithium isotopes by using organic liquid film extraction system of crown ether-ionic liquid

The organic liquid film extraction system, a novel extraction system, was investigated for the extraction and separation of lithium isotopes using ionic liquid as the co-extractant and Dibenzo-15-crown 5-Ether (DB15C5) as the extractant. Multiple subjects were studied during the investigation, including the effects of extraction time; gas flow rate; temperature; counter anions of lithium salt; the length of the cationic carbon chain of ionic liquid on extraction, and separation of lithium isotopes. The maximum separation factor α was 1.037 ± 0.002 and the abundance of 6Li increased from 7.61 % to 7.86 %. Based on the slope analysis method, the formation of 1:1 complex [Li (DB15C5)]+ in the extraction phase was determined. The exchange of lithium isotope is spontaneous reaction at low temperatures (ΔH<0, ΔS<0). Also, the back-extraction times of lithium ions from extraction phase to aqueous phase were studied.

Destabilization effect of imidazolium cation-Hofmeister anion salts on cytochrome c

We have analyzed an effect of imidazolium cation-Hofmeister anion salts on stability of basic horse heart cytochrome c (cyt c) at pH4.5 (net charge +17). The effect of salts consisting of imidazolium cations, 1-ethyl-3-methylimidazolium (EMIm+) and 1-butyl-3-methylimidazolium (BMIm+), and five anions: chloride, bromide, iodide, nitrate, and thiocyanate on thermal and pH stability of cyt c was compared with the effect of corresponding sodium salts. Correlation between parameter of dTtrs/d [ion] (Ttrs; thermal midpoints) with surface tension changes of solvent in the presence of both imidazolium and sodium salts implies direct interaction between ions and proteins. Surprisingly, the imidazolium salts have more pronounced destabilization effect on highly positively charged cyt c than the corresponding sodium counterparts. Our analysis suggests the direct interaction of imidazolium cations with polypeptide chain, in analogy to guanidium cation, but the destabilization effect is significantly strengthened by decreased surface tension of imidazolium salt solvents. Comparison of an effect of imidazolium and sodium salts on acidic and alkaline transitions and to thermal transition of cyt c implies a role of hydrophobic interaction between imidazolium cation and polypeptide chain.

Self-organization in l-cysteine-silver acetate-D2O solutions at low-concentrations

Supramolecular hydrogels based on solutions of l-cysteine and silver acetate at low-concentrations in heavy water (D2O) were prepared. Processes of self-organization of l-cysteine and silver acetate in plain and heavy water have been investigated using UV spectroscopy, dynamic light scattering, and NMR spectroscopy. A replacement of H2O with D2O causes aging of the cysteine-silver solution, and resulting particles in the solution are larger in size. A possible structure of the supramolecular aggregate was proposed using NMR spectroscopy, and the mechanism of its interaction with the salt anions introduced into the system upon the formation of resulting hydrogels was verified.

Dissecting the Effect of Salt for More Sensitive Label-Free Colorimetric Detection of DNA Using Gold Nanoparticles.

Taking advantage of the protection effect of single-stranded DNA oligonucleotides, gold nanoparticles (AuNPs) remain dispersed and retain a red color with the addition of a low concentration of salt, while AuNPs would aggregate in the presence of double-stranded DNA. This difference has been used to design label-free colorimetric sensors for DNA detection. NaCl is the most commonly used salt to induce the aggregation of AuNPs. In this work, we aimed to test if other salts can provide even better sensor performance and to understand the effects of the cations and anions in salts. We first studied the effect of anions, including halides (NaF, NaCl, NaBr, and NaI), and other common salts (NaNO3, NaClO4, Na2SO4, Na2S2O3, sodium phosphate, and sodium citrate). Among them, weakly adsorbing ones such as F-, citrate, and phosphate appeared to yield better sensitivity than Cl-. Anions can directly adsorb on the AuNPs and affect DNA adsorption. We then tested cations, and only group 1A metals (LiCl, NaCl, KCl, RbCl, and CsCl) can signal DNA adsorption, while divalent metals (MgCl2, CaCl2, MnCl2, and NiCl2) barely showed the effect of DNA. CsCl only works for strongly adsorbing DNA, such as A15, but not weakly adsorbing T15. Overall, NaF is a better salt than NaCl by having a 2.3-fold higher sensitivity, which was confirmed in a DNA sensing assay. This work has identified a better salt yielding higher sensitivity, and sensing work relying on the change of the aggregation state of AuNPs can benefit from this study.

The Hofmeister effect on protein hydrogels with stranded and particulate microstructures

The infiltration of ions into hydrogel matrix could significantly affect the microstructure and macroscopic mechanics of the gels. Here, the Hofmeister effect of various salts on the whey protein isolate hydrogels with fine-stranded and particulate microstructures is investigated by soaking the preformed hydrogels in the sodium salts of different anions. The infiltration of kosmotropic anions yield stiffer hydrogels, whereas the chaotropic anions soften the hydrogels. The hydrogels with fine-stranded microstructures are more sensitive to the salts comparing to the particulate ones due to the microscopic phase transitions and enhanced hydrophobic interactions between polymer chains occurred in fine-stranded hydrogels. Besides, despite the significant difference in water binding ability of different salts, the water holding capacity of the salt-treated hydrogels was mainly determined by the gel stiffness instead of the salt types. Similar mechanical responses of BSA and egg white protein hydrogels to the Hofmeister series was also demonstrated, suggesting that the results shown here could potentially be generalized for other globular protein hydrogels.

Structure, optical and magnetic properties of radical anion, dianion salts and coordination complexes of organic dye 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA)

Reduction of organic dye 3,4:9,10-perylenetetracarboxylic dianhydride (PTCDA) yields a series of radical anion and dianion salts of PTCDA (1–5). Their formation is accompanied by essential red shift and splitting of absorption bands of pristine PTCDA (493 and 560 nm) which appear nearly in the whole visible range, namely, at 660, 700 and 760–770 nm for the radical anions, and 514–526, 544–569, 633–644 and 700–713 nm for the dianions. Weaker bands are also observed in the NIR range at 954 and 938–940 nm, respectively. Reduction elongates double CO bonds, and the shape of the anions becomes non-planar due to twisting. A dihedral angle between two planar halves of PTCDA increases together with anion charge. The PTCDA•− radical anions form {PTCDA}22− dimers in 1–3 with short interplanar distances of 3.220–3.299 Å. These dimers show intense charge transfer bands at 1460–1480 nm and they are diamagnetic up to 360 K indicating large singlet-triplet energy gap for them. The dianions are diamagnetic in the salts. The PTCDA2− dianion can also form coordination complexes coordinating two potassium cations in {cryptand(K+)}2(PTCDA2−)⋅C6H4Cl2 (6) or vanadocene cation in {cryptand(K+)}(Cp2V+)(PTCDA2−)⋅C6H4Cl2 (7). Mixed {cryptand(K+)}2(PTCDA2−){GaIIICl(Pc•3−)}•−⋅2C6H4Cl2 (Pc: phthalocyanine, 8) salt containing two strongly absorbing anionic chromophores has also been obtained. Both anions are chequered in the layers forming short CO(PTCDA2−)⋅⋅⋅H[GaIIICl(Pc•3−)}•−] hydrogen bonds. Most probably, namely these bonds provide rather effective antiferromagnetic coupling of the [GaIIICl(Pc•3−)}•−] spins (S = 1/2) within the layers with large negative Weiss temperature of −25 K.

Green Synthesis of Triazole-Based Chemosensors and their Efficacy Towards Mercury Sensing

Background: The synthesis of small organic molecules based Hg2+ ions receptors have gained considerable attention because it is one of the most prevalent toxic metals which is continuously discharged into the environment by different natural and industrial activities. 1,4-Disubstituted 1,2,3-triazoles have been reported as good chemosensors for the detection of various metal ions including Hg2+ ions. Methods: The synthesis of 1,2,3-triazoles (4a-4c) was achieved by Cu(I)-catalyzed azide-alkyne cycloaddition, and their binding affinity towards various metal ions and anions were studied by UVVisible titration experiments. The perchlorate salts of metal ions and tetrabutylammonium salts of anions were utilized for the UV-Visible experiments. DFT studies were performed to understand the binding and mechanism on the sensing of 4a toward Hg2+ using the B3LYP/6-311G(d,p) method for 4a and B3LYP/LANL2DZ for 4a-Hg2+ species on the Gaussian 09W program. Results: The UV-visible experiments indicated that the compounds 4a-4c show a selective response towards Hg2+ ion in UV-Visible spectra, while other ions did not display such changes in the absorption spectra. The binding stoichiometry was evaluated by Job’s plot which indicated the 1:1 binding stoichiometry between receptors (4a-4c) and Hg2+ ion. The detection limit of 4a, 4b and 4c for the Hg2+ ions was found to be 29.1 nM, 3.5 μM and 1.34 μM, respectively. Conclusion: Some 1,2,3-triazole derivatives were synthesized (4a-4c) exhibiting high selectively and sensitivity towards Hg2+ ions in preference to other ions. Compound 4a has a low detection limit of 29.1 nM and the binding constant of 2.3×106 M-1. Similarly, 4b and 4c also showed selective sensing towards Hg2+ ions in the μM range. The observed experimental results were corroborated by density functional theory (DFT) calculations.

Evaluating Solid-Electrolyte Interphases for Lithium and Lithium-free Anodes from Nanoindentation Features

Summary The morphology and mechanical property of SEIs for lithium anodes crucially affect the electrochemical cycling performance of Li-metal batteries such as Li-S and Li-O2 batteries. Herein, we establish the standards for rapidly assessing SEIs for Li and Li-free type of anodes by AFM nanoindentation features toward prediction of corresponding electrochemical performances. A series of single-layered and multi-layered SEIs with known composition and structures are purposely constructed. A set of unique nanoindentation features representative of mechanical properties of the basic SEIs are formed, serving as the standards for rapidly assessing the mechanical properties and electrochemical performances of unknown SEIs together with their Young’s modulus, smoothness, and thickness. To validate the applicability of the method, SEIs formed by electrochemical aging and formed on Cu substrates are further evaluated. Our work not only contributes to understanding the influence of SEIs on cycling performances but also provides a rapid way for screening SEIs.

Mitigating the Shielding Effect of Ether Oxygen in Poly(ethylene glycol) on Boron Atoms in Boron‐Doped Poly(ethylene glycol) Hybrid Polymer Electrolyte by Introducing Siloxane Spacers

AbstractDoping boron (B) atoms into poly(ethylene glycol) (PEG)‐based solid polymer electrolytes (B‐PEG) is believed to be an attractive method to increase the lithium‐ion transference number ( ) because of the interaction between the electropositive B atoms and the anions of lithium salts. However, this effect can be largely impeded by the interaction between B and the electronegative ether oxygen atoms in the attached PEG molecular chains, which is referred to as a shielding effect. Enlarging the distance between the center B atoms and the electronegative ether oxygens is believed to be an effective way to reduce such shielding effect. In this work, different number of siloxane spacing groups (Six) are introduced in between the B atom and ether oxygen in the B‐PEG macromolecules (B‐Six‐PEGs x=0,1,3,5). As the siloxane oxygen has less electronegativity to ether oxygen, the shielding effects should be weakened and the ability of B atoms to trap the anions of lithium salt will increase. As the introduction of siloxane groups into the B‐Six‐PEGs polymer electrolytes will also reduce the neat contents of both B and PEG, which has the opposite effect on the whole ionic conductivities and values, both the ionic conductivities and values of B‐Six‐PEGs electrolytes first increase then decrease along with x increases from 0 to 5 when the [Li+]:[EO] mole ratio is fixed at 1 : 10. The peak value exists at x=1. Meanwhile, both the mobilities of Li+ ions (confirmed via 7Li nuclear magnetic resonance (NMR) results) and bis(trifluoromethane) sulfonimide (TFSI−) anions (confirmed from Raman spectra analysis) get their maximum values when x=1. However, if both the concentrations of TFSI− and B atoms in B‐Six‐PEGs electrolytes are taken into consideration, the normalized diffusion coefficient of TFSI− anions obtained by molecular dynamic (MD) simulation decrease monotonically when x increases from 0 to 5. As the diffusion coefficient of TFSI− anions is determined by the interaction probability and strength of TFSI− and B atoms; these results confirm that the interaction between the B atoms and TFSI− anions increase with x. Namely, the deshielding effects of siloxane spacing groups on B atoms increase along with the increase of x in the B‐Six‐PEGs polymer electrolytes, while it levels off when x exceeds 3.

Charge-by-Charge Ion Pairing Preserves Fluorescence Emission

In this issue of Chem, Flood and co-workers demonstrate spatially and electronically isolated cationic dyes in crystalline charge-by-charge ion-pairing systems based on sandwiched [2 + 1]-type anion complexes of a π-electronic cyanostar macrocycle; these dyes exhibit fluorescent colors and intensities similar to those in solution.

Quantum chemical prediction of the spectroscopic properties and ionic composition of the molten NaF-AlF3 salts

The behavior of the ions in the molten NaF-AlF3 salts plays a significant role in aluminium reduction process. Many experimental and modelling works have been carried out to investigate the ionic composition of the molten cryolite, which are still controversial. In this study, a recent thermodynamic model was introduced to compare with the Temkin model, which was assumed to consist of F−, AlF4−, AlF52−, AlF63−, Al2F7−, Al2F93−, Al2F104−, and Al3F145−. The thermodynamic calculations were performed to investigate the influence of the cryolite ratios on the ionic composition of the molten NaF-AlF3 and calculate the fractions of all the possible anions in the molten salts. On the other hand, the Raman spectra of the fluoro-aluminate ionic clusters were obtained by the quantum chemical calculations considering the existence of the cations Na+ and the number of the ionic pairs in the structural models of the ionic clusters, which were used to parsing the high temperature in situ Raman spectrum of the molten cryolite. The ionic composition of the molten salts was discussed based on the thermodynamic calculations and the fitting results of the high temperature in situ Raman spectrum of the molten cryolite.

Improvement of Lithium Metal Polymer Batteries through a Small Dose of Fluorinated Salt.

Introducing a small dose of an electrolyte additive into solid polymer electrolytes (SPEs) is an appealing strategy for improving the quality of the solid-electrolyte-interphase (SEI) layer formed on the lithium metal (Li°) anode, thereby extending the cycling life of solid-state lithium metal batteries (SSLMBs). In this work, we report a new type of SPEs comprising a low-cost, fluorine-free salt, lithium tricyanomethanide, as the main conducting salt and a fluorinated salt, lithium bis(fluorosulfonyl)imide (LiFSI), as the electrolyte additive for enhancing the performance of SPE-based SSLMBs. Our results demonstrate that a homogeneous and stable SEI layer is readily formed on the surface of the Li° electrode through the preferential reductive decomposition of LiFSI, and consequently, the cycle stabilities of Li°||Li° and Li°||LiFePO4 cells are significantly improved after the incorporation of LiFSI as an additive. The intriguing chemistry of the salt anion revealed in this work may expedite the large-scale implementation of SSLMBs in the near future.

Manganese (II)-imidazole complexes of the non-steroidal anti-inflammatory drug mefenamic acid: Synthesis, and structural studies

Two new complexes of Mn(II) have been synthesized with a non-steroidal anti-inflammatory drug, mefenamic acid, 2-[(2,3-dimethylphenyl)amino]benzoic acid (mef) and the nitrogen donor ligands; imidazole (imi) and 2-methylimidazole (mei), viz. [Mn(mef)2(imi)2(EtOH)2]; M−1 and [Mn(mef)2(mei)2(EtOH)2]; M−2. Also, when mefenamic acid interacted with MnCl2·4H2O in the presence of 2-aminopyridine (apy), a salt of ((mef)(apy)(H2O)); M−3 was isolated. The complexes were characterized using elemental analysis, FTIR, UV–Visible (M−1 and M−2), and single-crystal X-ray diffraction studies. Monodentate coordination of the mefenamate ligand in M−1 and M−2 was confirmed from the FTIR studies. The X-ray structural analysis shows that the two Mn(II) complexes and one salt crystallize in the triclinic space group P-1. M−1 consists of monomeric Mn(II) in hexacoordination with two monodentate mefenamate, two imidazoles, and two ethanol solvent ligands. M−2 consists of monomeric Mn(II) complex in octahedral geometry and coordinated to two each of monodentate mefenamate, 2-methylimidazole, and two ethanol solvent ligands. M−3 consists of salt of mefenamate anion linked to an aminopyridinium cation, with a hydrogen-bonded water molecule present in the crystal lattice which connects the cation and anion via intermolecular OH···O and NH···O interactions.

Toward a Reversible Mn4+/Mn2+ Redox Reaction and Dendrite‐Free Zn Anode in Near‐Neutral Aqueous Zn/MnO2 Batteries via Salt Anion Chemistry

AbstractRechargeable aqueous Zn/MnO2 batteries are very attractive large‐scale energy storage technologies, but still suffer from limited cycle life and low capacity. Here the novel adoption of a near‐neutral acetate‐based electrolyte (pH ≈ 6) is presented to promote the two‐electron Mn4+/Mn2+ redox reaction and simultaneously enable a stable Zn anode. The acetate anion triggers a highly reversible MnO2/Mn2+ reaction, which ensures high capacity and avoids the issue of structural collapse of MnO2. Meanwhile, the anode‐friendly electrolyte enables a dendrite‐free Zn anode with outstanding stability and high plating/stripping Coulombic efficiency (99.8%). Hence, a high capacity of 556 mA h g−1, a lifetime of 4000 cycles without decay, and excellent rate capability up to 70 mA cm−2 are demonstated in this new near‐neutral aqueous Zn/MnO2 battery by simply manipulating the salt anion in the electrolyte. The acetate anion not only modifies the surface properties of MnO2 cathode but also creates a highly compatible environment for the Zn anode. This work provides a new opportunity for developing high‐performance Zn/MnO2 and other aqueous batteries based on the salt anion chemistry.

Anion effect on the cumene hydroperoxide decomposition in the presence of Cu(II) 1,10-phenanthrolinates

Kinetics of the cumene hydroperoxide catalytic decomposition in the presence of Cu(II) salt complexes with 1,10-phenanthroline (Phen) has been investigated in the water: ethanol (1:1) solvent mixture. Catalytic properties of Cu(CH3COO)2 - Phen complex were confirmed: after full hydroperoxide conversion its new portion had been added to the reaction mixture. The hydroperoxide decomposition rate constant observed on the second cycle was the same. The salt anion effect on the complex catalytic activity has been revealed. The rate constant of the cumene hydroperoxide catalytic decomposition increases in the following row of anions: SO42− < Cl− < CH3COO−, the hydroperoxide decomposition in the presence of Cu(II) nitrate in the same experimental conditions was not observed. The effect of the anion nature in the reaction of cumene hydroperoxide catalytic decomposition may be associated with both the structure of the Cu(II) complex with Phen, as well as the structure of the hydroperoxide - catalyst complex. In addition, the double activation effect is observed in the reaction considered. The hydroperoxide molecule is chemically activated by the corresponded Cu(ІІ) salt. The Cu(ІІ) salt reactivity by-turn is activated in the presence of 1,10-phenanthroline and can be regulated by means of variation in corresponded salt anion.

A flexible Cellulose/Methylcellulose gel polymer electrolyte endowing superior Li+ conducting property for lithium ion battery

With the advent of gel polymer electrolyte (GPE), a series of safety problems of lithium ion batteries have been resolved. However, poor self-standing property, the low ionic conductivity and Li+ transference number are still the obstacles that impede the practical application of GPE. Herein, a flexible and eco-friendly GPE is designed using allyl-modified cellulose with methylcellulose through simple UV curing. The crosslinked structure facilitates the integrity of GPE during use, and methylcellulose guarantees the high affinity to liquid electrolyte and improve interfacial compatibility. The specific polar functional groups (OH, OCH3 and COC) in GPE cooperate to enhance the lithium salt dissociation, anion immobilization and lithium ion transporting and enable the high Li+ transference number (0.902) and ion conductivity (4.36 × 10-3 S cm-1). The assembled Li/GPE/LiFePO4 coin cells possess high initial discharge capacity of 150.6 mA h g-1 and a high capacity retention of 91.6 % after 100 cycles.

Synthesis, structure, spectra, magnetism, non-linear optical properties and DFT calculations of a bis(dithiolene)nickel(III) anion salt with substituted isoquinolinium

Self-assemble of the bis(maleonitriledithiolate)nickel(III) anion ([Ni(mnt)2]−) and 4-cyanobenzyl isoquinolinium cation ([4CNBzIQl]+) results into a new molecular solid, [4CNBzIQl][Ni(mnt)2](1). Single crystal X-ray diffraction revealed that contains segregated columns of anions and cations and the Ni(III) ions form a 1 D zigzag alternating chain through Ni···S and π···π interactions between anions. Powder XRD diffraction study confirms the crystalline nature of the title material. The UV-Vis spectral analysis was used to determine the band gap energy, and the nonlinear optical (NLO) effect of the compound was predicted using DFT. Upon the temperature is lowered, the non-uniform chain has been compressed with the change of Ni···Ni distance, and a spin gap transition around 128 K.