Thermodynamics of ion exchange in a sulfonated polymer based on <Emphasis Type="Italic">cis</Emphasis>-tetraphenylmetacyclophanoctol

The thermodynamic characteristics of proton exchange in SO₃H groups of a sulfonated network polymer based on cis-tetraphenylmetacyclophanoctol for Na⁺, Cu²⁺ cations from aqueous solutions were considered for the first time. Microcalorimetric measurements of the heat effects of N^a+-H⁺ and Cu²⁺-H⁺ exchanges were performed, equilibrium compositions of polymer and solution were determined. The changes of Gibbs energy, enthalpy and entropy of ion exchange were calculated.     

Ion-exchange selectivity of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene

The ion-exchange equilibrium of protons in SO₃H groups of a sulfonic cation exchanger based on immobilized cis-tetraphenylcalix[4]resorcinolarene with cations of Li⁺, Na⁺, Ag⁺, Cu²⁺, In³⁺, and protonated 1,3,5,7-tetraazaadamantane in aqueous solutions of electrolytes at 293 K was studied. The corrected coefficients of the cation exchange selectivity were calculated.     

Sorption of transition metal cations on natural heulandite

The cation exchange equilibrium in the systems of natural heulandite-binary aqueous solutions of NaCl, NiCl₂, CuCl₂, ZnCl₂, and MnCl₂ was studied. The corrected coefficients of the selectivity (k ^a _M/Na) and thermodynamic constants (K _M/Na) of the cation exchange of Na⁺ cations for transition metal cations were determined. The selectivity of the cation exchange on natural heulandite increases in the following order: Ni²⁺ < Cu²⁺ < Zn²⁺ < Na²⁺ < Mn²⁺.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1101–1103, May, 1996.     

Oberflächenzusammensetzung,Löslichkeit und Ionenaktivitätsprodukt von Calcit in fremdionenhaltigen Lösungen

Surface Composition, Solubility, and the Ion Activity Product of Calcite in Solutions with Auxiliary Ions Using the method of simultaneous ion and isotope exchange the chemical composition of the surface layer of calcite powder in equilibrium with solutions of varying Me/Ca molar ratios is determined (Me = Mg²⁺, Co²⁺, Ni²⁺, and Fe²⁺ ions). The ion exchange isotherms show a marked bend in the surface reactivity when a surface molar ration of ～1 and ～3 is reached. The solubility of calcite initially decreases on the addition of Co²⁺ or Ni²⁺ ions to the solution whereas it increases in the presence of Mg²⁺ or Fe²⁺ ions. The activity product of the pseudo compound, Ca_xMe_(1–x)CO₃, decreases in the Ni²⁺, Co²⁺ or Fe²⁺ exchange experiments, however, it increases considerably in those with Mg²⁺ ions.     

Polymer complexes. LXXVI. Synthesis,characterization, CT‐DNA binding,molecular docking and thermal studies of sulfoxine polymer complexes

Novel polymer complexes of 8‐hydroxyquinoline‐5‐sulfonic acid hydrate ( H ₂ L ) with Cu²⁺, Co²⁺ and Ni²⁺ chloride were prepared and characterized. Microanalysis, magnetic susceptibility, IR spectra, electron spin resonance, mass spectra, X‐ray, molar conductance, thermal, and UV–Vis spectra studies have been used to confirm the structure of the prepared polymer complexes. The molecular and electronic structures of the hydrogen bond conformers for ligand ( H ₂ L ) were optimized theoretically and the quantum chemical parameters were calculated. On the basis of elemental and IR data, the chemical structure of metal chelates commensurate that the tri‐dentate (H₂L) coordinate to metal chlorides through oxygen atom of phenolic OH and oxygen atom of SO₃‐H group by replacing H atoms and nitrogen of the quinoline ring. The magnetic studies suggested the octahedral geometrical structure for all produced polymer complexes with general formula {[ML (OH₂)₃] .xH₂O}_n (M = Cu²⁺, x = 1.; Co²⁺, x = 2 and Ni²⁺, x = 2) in molar ratio (1:1). Coats–Redfern and Horowitz–Metzger methods have been used for calculating the activation thermodynamic parameters of the thermal decomposition for H ₂ L and its polymer complexes. The interaction between H ₂ L and its transition metal complexes with the calf thymus DNA (CT‐DNA) was determined by UV–Vis spectra. Binding efficiency between H ₂ L with the receptors of the prostate cancer (PDB code 2Q7L Hormone) and the breast cancer (PDB code 1JNX Gene regulation) was studied by molecular docking. The inhibition behaviour of H ₂ L against the corrosion of carbon steel / HCl (2 M) solution was studied by weight loss, Tafel polarisation, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. The adsorption isotherm was found to be Friendlish isotherm. The morphology of inhibited carbon steel? s surface was studied using scanning electron microscope (SEM) and energy dispersive X‐ray spectroscopy (EDS).     

Gas-phase synthesis of lanthanide(III) benzoates Ln(Bz)<Subscript>3</Subscript> (Ln = La,Tb, Lu)

A new method for the synthesis and film deposition of nonvolatile aromatic lanthanide(III) carboxylates by ligand exchange reaction between the starting volatile components in the gas phase was proposed. The complexes Ln(Bz)₃ (Ln = La³⁺, Tb³⁺, Lu³⁺, HBz = benzoic acid) were synthesized by gas-phase ligand exchange reaction between the volatile Ln(Thd)₃ and HBz (HThd = 2,2,6,6-tetramethylheptane-3,5-dione). The composition of the complexes was confirmed by elemental, thermal, IR-spectroscopic, and photoluminescence analyses and, in the case of lanthanum and lutetium complexes, by ¹H NMR.     

Cation exchange membranes as solid solutions

The ion exchange equilibrium between KCl and SrCl₂ solutions and the cation selective membrane CR61 AZL386 has been examined. Equilibrium isotherms are measured for membrane—electrolyte equilibria for two total concentrations of Cl^?in the electrolyte solution and at three different temperatures. The results show that Sr²⁺ is strongly preferred to K⁺ in the membrane. Selectivity increases with temperature in the range 10°C to 40°C. It decreases with increasing total concentration from 0.01 N to 0.03 N. Electrolyte absorption in the membrane was not detected for the experimental conditions used. Contents of water in the membrane is constant for external salt concentrations between 3 x 10^?8N and 3 x 10^?2N. The difference in water content between the pure K form and the pure Sr form is approximately 5%.A thermodynamic treatment of ion exchange is presented. The thermodynamic equilibrium constant for the exchange reaction 2 KR + SrCl₂ = SrR₂+ 2 KCl has been determined by two different integration procedures, R being an ion exchange site in the membrane. The variations of the thermodynamic functions ΔG_mix, ΔH_mix and ΔS_mix are calculated from experimental data for an assumed mixing process of membranes in the pure forms.Activity coefficients for the membrane components are calculated from experimental data. Results are compared to two lattice models. A model with a random distribution of K⁺, Sr²⁺ and a vacant site seems preferred at low concentration of Sr²⁺. At high concentrations, Sr²⁺ and the vacant site associate.     

Thermodynamic behavior of complexation of 18-crown-6 with Tl<Superscript>+</Superscript>, Pb<Superscript>2+</Superscript>, Hg<Superscript>2+</Superscript>, and Zn<Superscript>2+</Superscript> metal cations in methanol-water binary media

The equilibrium constants and thermodynamic parameters for complex formation of 18-Crown-6 (18C6) with Tl⁺, Pb²⁺, Hg²⁺, and Zn²⁺ metal cations have been determined by conductivity measurements in methanol (MeOH)-water (H₂O) binary solutions. 18-Crown-6 forms 1:1 complexes with Hg²⁺ and Zn²⁺ cations, but in the case of Tl⁺ and Pb²⁺ cations, in addition to 1:1 stoichiometry, 1:2 (ML₂) complexes are formed in some binary solvents. The thermodynamic parameters (ΔH _c⁰ and ΔS _c⁰), which were obtained from the temperature dependences of equilibrium constants, show that in most cases the complexes are enthalpy destabilized but entropy stabilized. Non-linear behavior is observed between the equilibrium constants (log K _f ) of complexes and the composition of the mixed solvent. The selectivity of the ligand for these metal cations is sensitive to the solvent composition, and, in some cases, the selectivity order is reversed in certain compositions of the mixed solvent. The results also show that the mechanism of complexation reactions and the stoichiometry of complexes of some metal cations change with the nature and even with the composition of the mixed solvent. The article was submitted by the authors in English.     

Phase equilibria in the PbSe-Bi<Subscript>2</Subscript>Se<Subscript>3</Subscript>-Se system and thermodynamic properties of intermediate phases

The Pb-Bi-Se system in the PbSe-Bi₂Se₃-Se-Se composition region was studied by measurement of concentration circuits of the type (−) PbSe(solid) liquid electrolyte, Pb²⁺(Pb-Bi-Se)(solid) (+) in the temperature range 300–430 K and by X-ray powder diffraction. A solid-phase equilibrium diagram was constructed, and the formation was confirmed for the ternary compounds Pb₅Bi₆Se₁₄, Pb₅Bi₁₂Se₂₃, and Pb₅Bi₁₈Se₃₂, which belong to the homologous series [(PbSe)₅] _m · [(Bi₂Se₃)₃] _n . From the emf versus temperature equations, the partial thermodynamic functions [`(DG)]\overline {\Delta G}, [`(DH)]\overline {\Delta H}, [`(DS)]\overline {\Delta S} of PbSe in alloys were calculated. Based on the solid-phase equilibrium diagram from these partial molar quantities using the corresponding data for PbSe and Bi₂Se₃, the standard thermodynamic functions of formation and standard entropies of the above ternary compounds were calculated.     

Solvent extraction of Pu(IV) with TODGA in C6mimTf2N

Studies on the solvent extraction of Plutonium(Pu(IV)) from aqueous nitric acid by N,N,N′,N′-tetraoctyl-diglycolamide (TODGA) in 1-hexyl-3-methylimidazolium-bis(trifluoromethylsulfonyl) imide (C₆mimTf₂N) room temperature ionic liquid (RTIL) were carried out. It was found that Pu(IV) is extracted into RTIL phase as [Pu(NO₃)(TODGA)]³⁺ through cation exchange mechanism. Extraction reaction equation is obtained by the influence of acidity and extractant concentration, and the parameters of thermodynamic equilibrium constant was calculated.     

Synthesis and Properties of Poly(Organophosphazenes) Electrolyte

Abstract

To prepare electrolytes using poly(organophosphazenes), poly(bisanilinophosphazene) selected was carried out with the various concentration of sulfonic chloride in tetra-chloroethane solvent using vigorously sterring at room temperature for 4 hr. The products prepared were determined with IR and chemical analysis. It was found that the -SO₃H groups in the product appeared at 1,1050 cm^?1, 1,030 cm^?1 and 550 cm^?1, and the reaction rate of sulfonic chloride was about 34%-55% under this experimental conditions. Also, the products had two kind of glass transition temperatures such as 63°C and -18°C, respectively, and the values were lower in comparison with that of starting polymer. Furthermore, the conductivity of the product at room temperature was determined and the conductivity was increased the concentration of -SO₃H groups. It was found that the product having -SO₃H groups was able to ion exchange with Li⁺ or Cu²⁺ ions under aqueous solution. Also, the ion exchange rate was determined with the titration of alkaline aqueous solution with a standard solution of HCl. The products formed after the ion exchange reaction had higher conductivity in comparison with that of the polymer.     

Gas-phase reactivity and molecular modeling studies on triply protonated dodecapeptides that contain four basic residues

Gas-phase deprotonation and hydrogen/deuterium (H/D) exchange reactions for ions from three model dodecapeptides were studied by Fourier transform ion cyclotron resonance mass spectrometry. Molecular dynamics calculations were employed to provide information on conformations and Coulomb energies. The peptides, (KGG)₄, (K₂G₄)₂, and K₄G₈, each contain four high basicity lysine residues and eight low basicity glycine residues; however, in the present work only three lysine residues were protonated. Proton transfer reactions with a series of reference amines revealed apparent gas-phase acidities in a narrow range of 207. 3–209. 6 kcal/mol, with deprotonation efficiencies following the order [K₄G₈+3H]³⁺ > [(KGG)₄+3H]³⁺ > [(K₂G₄)₂+3H]³⁺. The three ions also react similarly with d ₄-methanol: each exchanged a maximum of 23–25 of their 25 labile hydrogens, with the first 15–17 exchanges occurring at rate constants of (1. 6–2. 6) × 10^?11 cm³ molecule^?1 s^?1. The experimental results agree with molecular modeling findings of similar conformations and Coulomb energies for the three peptide ions. The [M+3H]³⁺ data are compared to data obtained previously in our laboratory for the “fully” protonated [M+4H]⁴⁺ (Zhang, X.; Ewing, N. P.; Cassady, C. J. Int. J. Mass Spectrom. Ion Phys., in press). For (KGG)₄ and (K₂G₄)₂, there is a marked difference in H/D exchange reactivity between 3+ ions and 4+ ions. The 4+ ions, which have diffuse conformations, slowly exchange only 14 hydrogens, whereas their more compact 3+ counterparts exchange 23–25 hydrogens at a 5-times greater rate. In contrast, the 3+ and 4+ ions of K₄G₈ have similar compact conformations and exchange reactivity. The results indicate that a multiply hydrogen-bonded intermediate between the deuterating reagent and the peptide ion is necessary for facile H/D exchange. The slower, incomplete H/D exchange of [(KGG)₄+4H]⁴⁺ and [(K₂G₄)₂+4H]⁴⁺ is attributed to the inability of their protonated lysine n-butylamino groups (which extend away from the peptide backbone) to form this intermediate.     

Adsorption of UO2 2+, Tl+, Pb2+, Ra2+ and Ac3+ onto polyacrylamide-bentonite composite

Composite of polyacrylamide-bentonite (PAA-B) was prepared by direct polymerization in a suspension of bentonite (B), the composite was then modified by phytic acid (PAA-B-Phy). The parameters related to adsorption of UO₂ ²⁺ in absence and presence of 0.01M CaCl₂ and of natural radionuclides (Tl⁺, Pb²⁺, Ra²⁺ and Ac³⁺ in a leaching solution) onto PAA-B and PAA-B-Phy, and thermodynamics of the adsorption were investigated. Adsorption isotherms were of L and H types for the adsorption of UO₂ ²⁺ onto PAA-B and PAA-B-Phy, whilst for Tl⁺, Pb²⁺, Ra²⁺ and Ac³⁺ they were of C type for both adsorbents. Langmuir equilibrium constants for the adsorption of all studied ions onto PAA-B-Phy were significantly higher than those found for PAA-B. The thermodynamic parameters indicated that adsorption reactions are spontaneous in terms of adsorption free enthalpy. The composite of PAA-B and its modification by Phy have been used for the first time in this study. It is concluded that the composites can be practically used for adsorption and applied as adsorbent of radionuclides.     

Standard thermodynamic functions and constants of complex formation of Nd<Superscript>3+</Superscript> and La<Superscript>3+</Superscript> with L-asparagine in aqueous solutions at 298 K

The enthalpies of complex formation of L-asparagine (HAsn^±) with Nd³⁺ and La³⁺ ions are determined calorimetrically at 298.15 K and an ionic strength of 0.5 (KNO₃). The thermodynamic characteristics of the formation of the NdAsn²⁺, NdAsn²⁺, LaAsn₂⁺, and LaAsn₂⁺ complexes are calculated.     

Reactivity of cobaloxime bound to polystyrene chain by carbon–cobalt σ bond

The (alkyl)-bis(dimethylglyoximato)pyridinecobalt attached to polychloromethylstyrene by a cobalt–carbon bond was prepared by the reaction of Co(II)(DH)₂Py with polychloromethylstyrene in benzene. The fraction of p-vinylbenzyl·Co(DH)₂Py introduced to the polymer was 8.1 and 2.1 mole %. The photodecomposition of the polymer-bonded cobaloxime was investigated by following the change of the visible spectrum. The rate constant k_dec of the polymer-bonded cobaloxime was 1.1 × 10^?2 sec^?1 in benzene; it is one-fourth of that of its monomeric analog, benzyl·Co(DH)₂Py. The k_dec values of the cobaloximes were also measured in benzene–dimethyl sulfoxide mixed solvents, and the polymer effects were discussed. The dependence of the photodecomposition on energy of the irradiation light was investigated, and it was found that the absorption band near 470 nm is important for the photodecomposition of the cobalt–carbon bond. Spectroscopic measurements of the ligand exchange reaction of polymer-bonded cobaloxime with pyridine in dimethyl sulfoxide gave a larger equilibrium constant (1.2 × 10⁴ liter/mole) than that of benzyl·Co(DH)₂Py (9.4 × 10² liter/mole). The kinetic data of the ligand exchange reaction indicated that the larger equilibrium constant for the polymeric system is due to the smaller rate constant of the reverse reaction. The thermodynamic parameters were also obtained.     

Tris[3‐hydroxy‐2(1 H)‐pyridinonato]‐Komplexe von Al3+, Cr3+ und Fe3+ – Kristall‐ und Molekülstrukturen von 3‐Hydroxy‐2(1 H)‐pyridinon und Tris[3‐hydroxy‐2(1 H)‐pyridinonato]chrom(III)

Tris[3‐hydroxy‐2(1 H)‐pyridinonato] Complexes of Al³⁺, Cr³⁺, and Fe³⁺ – Crystal and Molecular Structures of 3‐Hydroxy‐2(1 H)‐pyridinone and Tris[3‐hydroxy‐2(1 H)‐pyridinonato]chromium(III) Tris[3‐hydroxy‐2(1 H)‐pyridinonato] complexes of Al³⁺, Cr³⁺ and Fe³⁺ are obtained by reactions of 3‐hydroxy‐2(1 H)pyridinone with the hydrates of AlCl₃, CrCl₃ or Fe(NO₃) in aqueous alkaline solutions as polycrystalline precipitates. The compounds are isotypic. X‐ray structure determinations were performed on single crystals of the uncoordinated 3‐hydroxy‐2(1 H)‐pyridinone ( 1 ) (orthorhombic, space group P2₁2₁2₁, a = 405.4(1), b = 683.0(1), c = 1770.3(3) pm, Z = 4) and of the chromium compound 3 (rhombohedral with hexagonal setting, space group R3c, a = 978.1(1), c = 2954.0(1) pm, Z = 6).     

Controlling Lanthanide Exchange in Triple‐Stranded Helicates: A Way to Optimize Molecular Light‐Upconversion

The kinetic lability of hexadentate gallium‐based tripods is sufficient to ensure thermodynamic self‐assembly of luminescent heterodimetallic [GaLn( L3 )₃]⁶⁺ helicates on the hour time scale, where Ln is a trivalent 4f‐block cation. The inertness is, however, large enough for preserving the triple‐helical structure when [GaLn( L3 )₃]⁶⁺ is exposed to lanthanide exchange. The connection of a second gallium‐based tripod further slows down the exchange processes to such an extent that spectroscopically active [CrErCr( L4 )₃]⁹⁺ can be diluted into closed‐shell [GaYGa( L4 )₃]⁹⁺ matrices without metal scrambling. This feature is exploited for pushing molecular‐based energy‐transfer upconversion (ETU) at room temperature.     

Evidence for Interchange Ligand‐Exchange Processes on Solvated Beryllium Cations

The ligand‐exchange mechanism of solvated Be²⁺ cations has been studied by means of DFT calculations (RB3LYP/6‐311+G**). Ligand exchange around [BeL₄]²⁺, where L=H₂O, NH₃, CO₂, formaldehyde (H₂CO), HCN, N₂, and CO, was found to follow an associative interchange (I_a) process in all cases. The size of the activation barrier is almost independent of the type of donor atom, and depends mainly on the hybridization undergone by the donor atom. This, in turn, suggests that steric effects play a major role in solvent‐ and ligand‐exchange reactions in Be²⁺ systems.     

Chemoselective Phototransformation of CH Bonds on a Polymer Surface through a Photoinduced Cerium Recycling Redox Reaction

It is generally accepted that Ce⁴⁺ is unable to directly oxidize unreactive alkyl C?H bonds without the assistance of adjacent polar groups. Herein, we demonstrate in our newly developed confined photochemical reaction system that this recognized issue may be challenged. As we found, when a thin layer of a CeCl₃/HCl aqueous solution was applied to a polymeric substrate and the substrate subjected to UV irradiation, Ce³⁺ was first photooxidized to form Ce⁴⁺ in the presence of H⁺, and the in situ formed Ce⁴⁺ then performs an oxidation reaction on the C?H bonds of the polymer surface to form surface‐carbon radicals for radical graft polymerization reactions and functional‐group transformations, while reducing to Ce³⁺ and releasing H⁺ in the process. This photoinduced cerium recycling redox (PCRR) reaction behaved as a biomimetic system in an artificial recycling reaction, leading to a sustainable chemical modification strategy for directly transforming alkyl C?H bonds on polymer surfaces into small‐molecule groups and polymer brushes. This method is expected to provide a green and economical tool for industrial applications of polymer‐surface modification.     

Thermodynamic characteristics of complexation between Ho<Superscript>3+</Superscript> and ethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>'-disuccinic acid in aqueous solutions at 298.15 K

The thermodynamic characteristics of complexation between ethylenediamine-N,N'-disuccinic acid (H₄Y; EDDA) and Ho³⁺ ion were determined calorimetrically and potentiometrically at 298.15 K and ionic strengths of 0.1, 0.5, 1.0, and 1.5 (KNO₃). The logK, Δ_rG, Δ_rH, and Δ_rS values for the formation of HoY^– and HOHY complexes were calculated at the studied and zero ionic strength values. The changes in thermodynamic parameters of the reactions are discussed.