CSF Solution Research Articles

Photochemical preparation of Cs[MF6] salts (M = Ru, Rh, Os, Ir, Pt); crystal structures and Raman spectra

Attempts to prepare Cs[MVIF7] and Cs2[MVIF8] salts by photochemical reactions between CsF, noble metal M (M = Ru, Rh, Os, Ir, Pt) and UV-irradiated F2 in anhydrous HF failed. The main products were Cs[MVF6] salts. The formation of MF6 (M = Rh, Os, Ir) was also observed. The reaction between PtF6 and a solution of CsF in anhydrous HF resulted in the formation of CsPtF6 and the release of elemental F2. The crystal structures of the Cs[MVF6] salts (M = Ru, Rh, Os, Ir, Pt) were determined on single crystals. They are isotypic and crystallize in the trigonal space group R ̅3 (No. 148), belonging to the KAsF6 (KOsF6) family of crystal structures. The Raman spectra of Cs[MF6] salts (M = Ru, Rh, Os, Ir, Pt) are also described.

Conductometric Analysis of Ion Equilibrium in Li<sup>+</sup>/F<sup>−</sup> and Mg<sup>2+</sup>/F<sup>−</sup> Hybrid Electrolyte Solutions

Fluoride shuttle batteries are expected to be innovative with high energy density superior to lithium-ion ones as on-board power-source for electric vehicles. However, the low solubility of fluoride ion in organic solvents makes it difficult to choose electrolytes. Kawasaki et al. have reported that no precipitation appears in γ-butyrolactone solution of CsF at high concentrations in the presence of excess amounts of Li+ or Mg2+ cation [M. Kawasaki, et al., J. Electrochem. Soc., 169, 110508 (2022).]. Such solutions are called hybrid electrolyte ones. In this study, we performed conductometric titration of Li+- or Mg2+-containing solutions with CsF solutions to elucidate the ion equilibrium. The titration curves were analyzed on models including precipitation of LiF or MgF2 and formation of Li2F+ and LiF2− triple ion or MgF+ associated one to evaluate the corresponding equilibrium constants. The results indicate that no precipitation appears in certain ranges of the F−/Li+ or F−/Mg2+ molar ratio by the triple/associated ion formation. Details of the conductometric analysis are discussed together with some problems involved in the proposed method.

X-Ray Crystal Truncation Rod Studies of Electrochemical Double Layers

Electrochemical double layers (EDL) is traditionally described as diffuse distributions of cations and anions, proposed in Gouy and Chapman (GC) model[1] and further developed extensively over decades largely based on voltammetry measurements. However, the GC model is suspected to break down at large potentials, because it predicts the unlimited rise in differential capacitance. Stern suggested long ago that there should be a layer with a finite ion density, known as ‘Stern layer’[2]. While it is generally accepted that Gouy-Chapman model or its modified versions describe well electrochemical interphase structures, recent studies of Pt(111) surface in CsF solution using a model-independent direct inversion method[3] have shown that Stern layer forms over the large double-layer potential range on Pt(111) surface.[4]In this talk, we present synchrotron x-ray observation of Electrochemical Stern layers on the surfaces of RuO2 single crystals in 0.1 M CsF electrolyte. It is of fundamental importance to study if Stern layer forms on electrode surfaces other than Pt(111). In this case, we will examine RuO2 surfaces and compare the results to that of Pt(111) surface. RuO2 is chosen for several reasons. First, it is a well-studied system because of its oxygen evolution reactions and we are familiar with the structure because of our previous studies.[5,6] Second, it is an oxide with oxygen terminated while Pt is a pure metal. Third, the surfaces of RuO2 are squares or rectangles while that Pt(111) surface is triangles. The Stern layers formed at the interfaces of RuO2 (110) and (100) are compared to the previously reported Stern layer on Pt(111). [4] While the Cs+ density profiles at the potentials close to hydrogen evolution reactions are similar, the hydration layers intervening the surface and the Cs+ layer are significantly denser on RuO2 surfaces than that on Pt(111) surface, reflecting the oxygen termination of RuO2 surfaces. The overall similarities between Stern layers on ruthenium surfaces and platinum surface suggest the universal presence of Stern layers in all well-defined solid-electrolyte interfaces.[1] Bard, A. J.; Faulkner, L. R., Electrochemical methods: fundamentals and applications. 2nd ed.; John Wiley: New York, 2001.[2] Stern, O., The theory of the electrolytic double layer. Zeitschrift Für Elektrochemie 1924, 30, 508.[3] Kawaguchi, T. et al., J. Appl. Cryst., 2018 51, 679.[4] Liu, Y.; Kawaguchi, T.; Pierce, M.S.; Komanicky, V.; You, H., Layering and Ordering in Electrochemical Double Layers, J Phys Chem Lett, 2018, 9, 1265.[5] Y.S. Chu, T.E. Lister, W.G. Cullen, H. You, Z. Nagy, Physical Review Letters 2001, 86, 3364.[6] Rao, R.R. et al., Journal of Physical Chemistry C, 2018, 122, 17802

Catalytic Asymmetric Fluorination of Copper Carbene Complexes: Preparative Advances and a Mechanistic Rationale.

The Cu‐catalyzed reaction of substituted α‐diazoesters with fluoride gives α‐fluoroesters with ee values of up to 95 %, provided that chiral indane‐derived bis(oxazoline) ligands are used that carry bulky benzyl substituents at the bridge and moderately bulky isopropyl groups on their core. The apparently homogeneous solution of CsF in C6F6/hexafluoroisopropanol (HFIP) is the best reaction medium, but CsF in the biphasic mixture CH2Cl2/HFIP also provides good results. DFT studies suggest that fluoride initially attacks the Cu‐ rather than the C‐atom of the transient donor/acceptor carbene intermediate. This unusual step is followed by 1,2‐fluoride shift; for this migratory insertion to occur, the carbene must rotate about the Cu−C bond to ensure orbital overlap. The directionality of this rotatory movement within the C 2‐symmetric binding site determines the sense of induction. This model is in excellent accord with the absolute configuration of the resulting product as determined by X‐ray diffraction using single crystals of this a priori wax‐like material grown by capillary crystallization.

In Situ Observation of Fluoride Shuttle Battery Reactions with Dissolution-Deposition Mechanisms by Raman Microscopy

Fluoride shuttle batteries (FSBs) are expected to have high energy densities. Evolution of FSB reactions, defluorination and fluorination of a nearly two-dimensional cluster of orthorhombic BiF3 microparticles partly embedded in a gold plating film (o-BiF3/gold) was studied by in-situ Raman microscopy. Solutions of fluorobis(2,4,6-trimethylphenyl)borane (FBTMPhB) and CsF (0.45 M and about 0.5 M (saturation)) in tetraglyme were used as electrolytes. During defluorination in the 0.45 M CsF solution, metallic bismuth appeared not only at positions of the cluster but also at positions of the gold plating, accompanying changes in morphology of the cluster, indicating that a dissolution-deposition mechanism (BiF3 → Bi3+ + 3F−, Bi3+ + 3e− →Bi) was operative in defluorination. Deposition of metallic bismuth preferentially occurred in the vicinity of the cluster, resulting in extension of protruding areas on the surface. BiF3 with a hexagonal structure appeared during fluorination together with change in the morphology of the cluster. With 0.5 M CsF solution, changes in morphology of the cluster during defluorination and fluorination were small, suggesting that the contribution of the dissolution-deposition mechanism was small. The observed changes in distribution and morphology of active materials will be useful information for designing better electrolytes and electrodes in future batteries.

Fractional Model of Couple Stress Fluid for Generalized Couette Flow: A Comparative Analysis of Atangana–Baleanu and Caputo–Fabrizio Fractional Derivatives

Different from a Newtonian fluid, couple stress uid (CSF) includes a new material constant, which is responsible for couple stress and the lubricant viscosity. This material constant comes with the fourth-order spatial derivative term, and due to this higher-order derivative term in the momentum equation, this uid (CSF) is comparatively less investigated even for the classical uid problems. This paper aims to study the fractional model of CSF, based on the Atangana-Baleanu (AB) fractional derivatives de nition. Since this AB de nition is new, therefore, for the sake of comparison and correctness, this problem is also solved using the Caputo-Fabrizio (CF) fractional derivative de nition. The CSF is considered to flow between two parallel plates, one of which is at rest and the other is moving with constant velocity. The external pressure gradient is also applied. This type of ow situations is usually called generalized Couette ow. The problem is rst written in dimensionless form and then solved for the exact solution using the Laplace transform and the nite Fourier sine transform. The CSF velocity obtained via an AB fractional derivative is compared with the CSF velocity obtained via a CF fractional derivative approach, and the results obtained are shown graphically. The CSF results for interesting uid parameters are displayed in various graphs for both the AB and CF fractional derivatives. It is observed that the CSF velocities obtained with the AB and CF fractional derivatives are the same for unit time. For time less than one and greater than one, variation in CSF velocities is observed. In limiting sense, the present CSF solutions are reduced to a similar Newtonian uid problem solution in the absence of external pressure gradient.

Evaluation of Efficacy of Different Identification Tests to Distinguish Cerebrospinal Fluid from Local Anaesthetic Solution: A Comparative Study

Background: Local anaesthetics (LAs) are used clinically for anaesthesia and analgesia either following surgery or for management of other acute and chronic pain conditions; they only last a few hours. Various methods have been mentioned in the past literature for differentiating the CSF and the local anaesthetic solutions. Hence; we planned the present study to check and compare the efficacy of simple identifications tests to distinguish local anesthetic solutions from CSF. Materials & Methods: We planned the present study to compare the efficacy of simple identifications tests to distinguish local anesthetic solutions from CSF. We involved five experienced anesthetists for the present study. Both the anesthetics were asked to identify 0.1 ml sample of bupivacaine and mock CSF (tap water) by each of four physicochemical characteristics based on criteria: Temperature, pH, Presence of glucose, and Turbidity when mixed with thiopentone. The anesthetics involved in the present study were unaware of the results. All the results were recorded on excel sheet and were analyzed by SPSS software. Results: The two test solutions were identified conveniently together with the four physiochemical tests. However; the anesthetics were not able to identify and differentiate the solutions clearly with individual tests. Conclusion: Anesthetist should be accustomed with different physicochemical methods available for differentiating between CSF and local anaesthetic solution. However; no single test appears to have complete reliability. Therefore, combinations of tests must be used.

Perfluoroalkylated Calix[4]pyrroles: Fluoride Ion Extraction from an Aqueous Medium.

Octaalkenyl calix[4]pyrrole ((CH2 =CH(CH2 )2 )8 C4P) is highly useful for the postfunctionalization of different calix[4]pyrroles with desired functionalities. Functionalization with perfluoroalkyl chains [CF3 (CF2 )n ; Rfn ] gave perfluoroalkyl calix[4]pyrroles (Rfn (CH2 )4 )8 C4P; n=6, 8), having >60 % fluorine content, which created a hydrophobic environment inside the calix[4]pyrrole cavity and recognized fluoride and chloride ions in solution as well as in the solid state. The fluoride ion is extracted efficiently from aqueous CsF and TBAF solutions by using (Rf6 (CH2 )4 )8 C4P, as droplets. The fluorinated chain generated a hydrophobic environment which broke the hydration shell associated with the anion and separated out fluoride ions as droplets from aqueous medium. Furthermore, the fluoride ions competitively replaced chloride ions from the (Rf6 (CH2 )4 )8 C4P cavity.

Solution nuclear magnetic resonance spectroscopy on a nanostructured diamond chip

Sensors using nitrogen-vacancy centers in diamond are a promising tool for small-volume nuclear magnetic resonance (NMR) spectroscopy, but the limited sensitivity remains a challenge. Here we show nearly two orders of magnitude improvement in concentration sensitivity over previous nitrogen-vacancy and picoliter NMR studies. We demonstrate NMR spectroscopy of picoliter-volume solutions using a nanostructured diamond chip with dense, high-aspect-ratio nanogratings, enhancing the surface area by 15 times. The nanograting sidewalls are doped with nitrogen-vacancies located a few nanometers from the diamond surface to detect the NMR spectrum of roughly 1 pl of fluid lying within adjacent nanograting grooves. We perform 1H and 19F nuclear magnetic resonance spectroscopy at room temperature in magnetic fields below 50 mT. Using a solution of CsF in glycerol, we determine that 4 ± 2 × 1012 19F spins in a 1 pl volume can be detected with a signal-to-noise ratio of 3 in 1 s of integration.

Cs(I) Cation Enhanced Cu(II) Catalysis of Water Oxidation.

We report here a new catalytic water oxidation system based on Cu(II) ions and a remarkable countercation effect on the catalysis. In a concentrated fluoride solution at neutral to weakly basic pHs, simple Cu(II) salts are highly active and robust in catalyzing water oxidation homogeneously. F(-) in solution acts as a proton acceptor and an oxidatively robust ligand. F(-) coordination prevents precipitation of Cu(II) as CuF2/Cu(OH)2 and lowers potentials for accessing high-oxidation-state Cu by delocalizing the oxidative charge over F(-) ligands. Significantly, the catalytic current is greatly enhanced in a solution of CsF compared to those of KF and NaF. Although countercations are not directly involved in the catalytic redox cycle, UV-vis and (19)F nuclear magnetic resonance measurements reveal that coordination of F(-) to Cu(II) is dependent on countercations by Coulombic interaction. A less intense interaction between F(-) and well-solvated Cs(+) as compared with Na(+) and K(+) leads to a more intense coordination of F(-) to Cu(II), which accounts for the improved catalytic performance.

ChemInform Abstract: Synthesis, Crystal Structure, and Properties of Pentadecafluorotetraantimonate(III) CsRb2Sb4F15.

AbstractSingle crystals of isostructural CsRb2Sb4F15 (I) and Cs3Sb4F15 (II) are obtained from aqueous solutions of RbF and/or CsF, and SbF3 in the molar ratios of 0.5:0.5:1 and 0.9:1, respectively.

Controlling flow direction in nanochannels by electric field strength.

Molecular dynamics simulations are conducted to study the flow behavior of CsF solutions in nanochannels under external electric fields E. It is found that the channel surface energy greatly affects the flow behavior. In channels of high surface energy, water molecules, on average, move in the same direction as that of the electric field regardless of the strength of E. In low surface energy channels, however, water transports in the opposite direction to the electric field at weak E and the flow direction is changed when E becomes sufficiently large. The direction change of water flow is attributed to the coupled effects of different water-ion interactions, inhomogeneous water viscosity, and ion distribution changes caused by the electric field. The flow direction change observed in this work may be employed for flow control in complex micro- or nanofluidic systems.

Effects of ITO Electrode Modification Using CsF Solution on Performance of Organic Light-Emitting Diodes

In this paper, the effects of indium tin oxide (ITO) surface modification on organic light-emitting diode performance are investigated. ITO electrodes were soaked in CsF solution of various concentrations and then subjected to ultraviolet (UV)-ozone treatment. The standard device structure is ITO/α-naphthylphenylbiphenyl diamine (NPB) (40 nm)/tris (8-hydroxyquinoline) aluminum (Alq3) (60 nm)/LiF (1 nm)/Al (150 nm). Modifying the ITO surface with the optimal 10 wt% CsF solution significantly improved device performance. The driving voltage was reduced from 3.5 V for standard devices to 3 V, the luminance was increased from 13200 to 20300 cd/m2, and the efficiency was increased from 2.8 to 3 cd/A. Work function estimates from Riken Keiki AC-2 measurements suggested that the work function of pristine ITO electrode was increased from 4.78 to 5.11 eV after modification. Measurements of energy band, surface energy and surface polarity indicated device improvement came from the simultaneous increase in work function and surface energy of ITO by soaking the ITO electrodes in the CsF solution followed by ultraviolet (UV)-ozone treatment.

ChemInform Abstract: Hydrothermal Chemistry, Structures, and Luminescence Studies of Alkali Hafnium Fluorides.

AbstractThe alkali hafnium fluorides Li2HfF6 (I), Na5Hf2F13 (II), K2Hf3OF12 (III), K3HfOF5 (IV), and (NH4)3HfOF5 (V) are hydrothermally prepared from aqueous solutions of HfF4, LiF, NaF, KF, KHF2, RbF, or CsF (sealed Ag ampule, autoclave, 400—600 °C, several days).

Ion Hydration Under Pressure: A Molecular Dynamics Study

This study is intended to elucidate the role of pressure on the hydration behaviour of ions in aqueous solutions. Molecular dynamics simulations were performed for systems modelling CsF, CsCl, CsBr, and CsI aqueous solutions under ‘normal’ (105 Pa, 298 K) and ‘high pressure’ (4 ·109 Pa, 500 K) conditions. Structural details are discussed in terms of radial distributions functions, coordination numbers, and instantaneous configurations of the ionic hydration shells. The dynamic properties studied include the velocity autocorrelation functions and self-diffusion coefficients of the ions for both pressure regimes. The results indicate strong changes in the hydration behaviour and mobility of the ions.

ChemInform Abstract: The Polymorphism of CsThF5.

AbstractThree new polymorphs of CsThF5 are hydrothermally synthesized from ThF4 and aqueous CsF solutions of varying concentrations in a silver ampule (autoclave, 575 °C, 2—12 d).

Water Mobility: A Bridge between the Hofmeister Series of Ions and the Friction of Zwitterionic Surfaces in Aqueous Environments

In this work, we systematically studied the effects of monovalent ions in the Hofmeister series on the friction of zwitterionic surfaces with carboxybetaine self-assembled monolayers (CB-SAMs) as model surfaces using molecular dynamics simulations. The friction coefficients between two CB-SAM surfaces under shear were calculated in the presence of LiCl, NaCl, KCl, CsCl, CsF, CsBr, or CsI solutions at 1 M. Results show that there is a strong correlation between the order of ions in the Hofmeister series and the friction of the CB-SAM surfaces. For salt solutions with the same anion, the friction of the surfaces in a solution with kosmotropic cations has larger friction than that in a solution with chaotropic ones. The same relationship between the order of ions in the Hofmeister series and the friction of the surfaces can be found for the salt solutions with the same cation but different anions. The analysis of water near the surfaces further suggests that these surfaces are hydrated with a similar amount ...

Intracerebral microdialysis during deep brain stimulation surgery

BackgroundThis report describes the use of microdialysis in conjunction with deep brain stimulation (DBS) surgery to assess extracellular levels of neurotransmitters within the human basal ganglia (BG). Electrical stimulation of the subthalamic nucleus (STN) is an efficacious treatment for advanced Parkinson's disease, yet the mechanisms of STN DBS remain poorly understood. Measurement of neurotransmitter levels within the BG may provide insight into mechanisms of DBS, but such an approach presents technical challenges. MethodsAfter microelectrode recordings confirmed location of STN, a custom microdialysis guide cannula was inserted. A CMA (Stockholm, Sweden) microdialysis probe was then positioned to the same depth as the microrecording electrode in STN or 2mm inferiorly to record in the substantia nigra. The catheter was perfused at a rate of 2.0μL/min with a sterile mock CSF solution and samples of extracellular fluid were collected at regular intervals. Dialysate samples were analyzed using high-pressure liquid chromatography (HPLC) detection procedures for quantitation of glutamate, gamma-aminobutyric acid (GABA), and dopamine. ResultsLevels of neurotransmitters were reliably identified in dialysate samples using HPLC. By monitoring concentrations of glutamate, GABA and dopamine, we were able to demonstrate what seemed to be a steady state baseline within approximately 30min. ConclusionMicrodialysis during DBS surgery is a feasible method for assessing levels of glutamate, GABA and dopamine within the human BG. Obtaining a steady state baseline of neurotransmitter levels appears feasible, thus making future studies of intraoperative microdialysis during DBS meaningful.

Hyperbaric oxygenation alleviates MCAO-induced brain injury and reduces hydroxyl radical formation and glutamate release

The present study examined the effect of hyperbaric oxygen (HBO) on the formation of 2,3-dihydroxybenzoic acid (2,3-DHBA) and 2,5-dihydroxybenzoic acid (2,5-DHBA), the products of salicylate trapping of hydroxyl free radicals, and glutamate release in the striatum during acute ischemia and reperfusion. Non-HBO rats (n = 8) were subjected to 1-h ischemia. Study rats (n = 8) were treated with HBO at 2.8 ATA for 1 h during ischemia. Artificial CSF solution containing 5 mM sodium salicylate was perfused at 1 microl/min. Samples were continuously collected at 15 min intervals and the levels of 2,3-DHBA, 2,5-DHBA, and glutamate were analyzed. The lesion volume was determined by TTC stain. Occlusion of the middle cerebral artery induced a significant increase in the levels of 2,3-DHBA and 2,5-DHBA. A peak of approximately two and fourfold of baseline levels was reached at 45 min and was maintained at elevated levels during reperfusion. The level of glutamate increased approximately two times at 30 min during ischemia, continued to increase, and reached approximately three times baseline level during reperfusion. HBO significantly alleviated brain injury associated with decreased levels of 2,3-DHBA, 2,5-DHBA and glutamate. This study suggests that the decreased glutamate release and the reduced formation of hydroxyl free radicals might contribute to the neuroprotective effect of HBO.

Central ventilatory control in the South American lungfish, Lepidosiren paradoxa: contributions of pH and CO2

Lungfish represent a probable sister group to the land vertebrates. Lungfish and tetrapods share features of respiratory control, including central, peripheral and intrapulmonary CO(2) receptors. We investigated whether or not central chemoreceptors in the lungfish, L. paradoxa, are stimulated by CO(2) and/or pH. Ventilation was measured by pneumotachography for diving animals. The fourth cerebral ventricle was equipped with two catheters for superfusion. Initially, two control groups were compared: (1) catheterized animals with no superfusion and (2) animals superfused with mock CSF solutions at pH = 7.45; PCO(2) = 21 mmHg. The two groups had virtually the same ventilation of about 40 ml BTPS kg(-1) h(-1) (P > 0.05). Next, PCO(2) was increased from 21 to 42 mmHg, while pH(CSF) was kept at 7.45, which increased ventilation from 40 to 75 ml BTPS kg(-1) h(-1). Conversely, a decrease of pH(CSF) from 7.45 to 7.20 (PCO(2) = 21 mmHg) increased ventilation to 111 ml BTPS kg(-1) h(-1). Further decreases of pH(CSF) had little effect on ventilation, and the combination of pH(CSF) = 7.10 and PCO(2) = 42 mmHg reduced ventilation to 63 ml BTPS kg(-1) h(-1).