Molar Electrical Conductivity Research Articles

Preparation and Characterization of Some Complexes of Nickel(II), Copper (II), and Zinc (II) With Decylxanthate and their Adducts with Nitrogen Base Ligands, and their Biological Activity

This research includes the synthesis and characterization of twelve new complexes of mono nuclear xanthate for a number of transition metal ions Ni(II), Cu(II), and Zn(II) and through the interaction with ligand (potassium decyl xanthate) and complexes of formula [M(DEXANT)2] were prepared: M= Ni(II), Cu(II), and Zn(II), and then the interaction of these complexes with Lewis bidentate bases, to give complexes with the formula [M(DEXANT)2.L], where L= 1,10-phenanthroline, 8-hydroxyquinoline, and 2,2-bipyridine. The prepared complexes were characterized by melting point, atomic absorption spectrometry, micro elemental analysis, infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, molar electrical conductivity, electronic absorption spectra, and magnetic susceptibility measurements. Magnetic moment and electronic spectra indicated that the complexes of type [M(DEXANT)2] had a tetrahedral geometry, while complexes of type [M(DEXANT)2.L] had an octahedral geometry. The conductivity measurements proved the non-electrolytic behavior of all compounds. The biological evaluation against bacterial species indicated that the xanthate complexes were effective against all bacterial types.

Synthesis, Characterization, and Biological Properties of the Copper(II) Complexes with Novel Ligand: N-[4-({2-[1-(pyridin-2-yl)ethylidene]hydrazinecarbothioyl}amino)phenyl]acetamide

For the first time, a thiosemicarbazone-type ligand containing a paracetamol structural unit was synthesized. Five new coordination compounds based on copper(II) salts: [Cu(L)CH3COO] (1), [{Cu(L)Cl}2]·H2O (2), [Cu(L)H2O·DMF]NO3 (3), [Cu(L)Br] (4), [Cu(L)H2O]ClO4 (5), were obtained, where HL is N-[4-({2-[1-(pyridin-2-yl)ethylidene]hydrazinecarbothioyl}amino)phenyl]acetamide. The new HL was characterized by NMR, FTIR, spectroscopy, and X-ray crystallography. All copper(II) coordination compounds were characterized by elemental analysis, FTIR, EPR spectroscopy, and molar electrical conductivity. Furthermore, single crystal X-ray diffraction analysis elucidated the structures of thiosemicarbazone HL as well as complexes 1–3. All compounds were tested for antimicrobial, antifungal, and antioxidant activities, and their toxicity to Daphnia magna was studied. Biological evaluation has revealed that most of the synthesized compounds demonstrate promising antibacterial, antifungal, and antioxidant activities. In many cases, their antibacterial/antifungal activity is comparable to that of certain drugs used in medicine for these purposes, and in some cases, even surpasses them. HL and complexes 2–5 exhibit antioxidant activity that surpasses that of Trolox. Furthermore, HL and complex 2 display virtually no toxicity to D. magna.

Copper(II) coordination compounds with 2-acetylpyridine N4-(bicyclo[2.2.1]heptan-2-yl)thiosemicarbazone as potential antibacterial agents

The paper presents the synthesis of the new 2-acetylpyridine N4-(bicyclo[2.2.1]hept-2-yl)thiosemicarbazone (HL) and its three copper(II) coordination compounds: [Cu(L)X] (X = NO3 - (I), Cl- (II), CHCl2COO- (III)). The obtained compounds were studied by NMR and FTIR spectroscopies, elemental analysis, and molar electric conductibility. The antibacterial activity towards Gram-positive (Staphylococcus aureus, Bacillus cereus) and Gram-negative (Escherichia coli, Acinetobacter baumannii) standard strains was studied for the HL and complexes I-III. The coordination of the HL to the copper(II) atom leads to the increase of activity against almost all microorganisms. Complex I is the most active one towards Gram-positive microorganisms, while complex III is the most active one towards Gram-negative microorganisms. They in many cases surpass the activity of Furacillinum and are practically on the same level as Tetracycline towards Gram-positive microorganisms.

Electrical Conductivity and Association of 1-butyl-3-methylpyridinium bis{(trifluoromethyl)sulfonyl}amide in Some Polar Solvents

The influence of alternating current frequency in the determination of the electrical conductivity of ionic liquids’ (ILs) dilute solutions in polar solvents has been considered. The frequency ranges in which the influence of polarization processes on electrodes occur and ionic relaxation occurs in the bulk of the solution have been excluded from the results of the electrical conductivity measurements. The association constants for Ka ILs in polar solvents published in literature were analyzed. A discrepancy between the values of Ka was noted, which is associated with the use of different calculation equations for electrical conductivity and the insufficiently correct consideration of the frequency dependance of the measured resistance. Based on the measured values of the electrical conductivity of dilute solutions of 1-butyl-3-methylpyridinium bis{(trifluoromethyl)sulfonyl}amide ([Bmpy][NTf2]) in acetonitrile (AN), dimethyl sulfoxide (DMSO) and dimethylformamide (DMF) in the 20--65 °C temperature range, the thermodynamic characteristics of the [Bmpy][NTf2] association were determined. The effect of temperature on the molar electrical conductivity of [Bmpy][NTf2] at infinite dilution λ0 and the association constant Ka have been considered. The Walden product (λ0η), where η is the viscosity of the solvent, was also analysed. It was shown that in AN, DMSO, and DMF, λ0η changes in different ways with increasing temperature; however, the value of λ0η/(εT) corrected for permittivity ε and absolute temperature T does not depend on the temperature and nature of the solvent. As the temperature rises, the electrical conductivity of the dilute solutions of [Bmpy][NTf2] increases in direct proportion to the ratio of the permittivity to dipole dielectric relaxation time of the solvent

Electrical Conductivity and Molar Volume of (LiCl-KCl)eut.–CsCl Molten Mixtures

The electrical conductivity of (LiCl-KCl)eut.–CsCl molten mixtures has been measured over a concentration range of 0–100 mol % CsCl and in a wide temperature span (624–1180 K). The measurements were carried out in quartz cells of the capillary type with platinum electrodes using the AC-bridge method. The molar volume of these mixtures was estimated using similar literature data. The maximum deviations of the molar volume from the additive values are ∼2%. Molar conductivity and its activation energy were calculated using the derived molar volume data. It was found that the electrical conductivity of all melts increases with increasing temperature and decreases with increasing CsCl concentration. In the molten (LiCl-KCl)eut.–CsCl mixtures, the significant negative deviations of the specific and molar electrical conductivities from additive values are observed over the whole concentration range, which indicates that the replacement of one alkaline cation by those, significantly different in size, is accompanied by a noticeable rearrangement of interparticle bonds. Therefore, the complexation in the system becomes different. According to the obtained data on electrical conductivity, the liquidus line of this system was built.

Preparation, thermal properties and electrical conductivity of solutions of pyridinium ionic liquids with tetrachloroferrate anion

Thermal stability of N -alkylpyridinium tetrachloroferrates(III) [C5H5NR]FeCl4 [R = C4H9, (CH2)3CN, CH2C6H5, C8H17, C10H21] in air in the range of 25-600°C was studied, as well as the thermal stability of N -alkylpyridinium chlorides. The equivalent electrical conductivity of N -alkylpyridinium tetrachloroferrates(III) in acetonitrile solution at 25°C was investigated. The ionic association constants K a , the limiting molar electrical conductivity (λ0) and the standard Gibbs energy of the association (Δ G °) in acetonitrile solutions were calculated based on conductometric data by the Lee-Wheaton method.

Novel Antioxidants Based on Selected 3d Metal Coordination Compounds with 2-Hydroxybenzaldehyde 4,S-Diallylisothiosemicarbazone.

2-Hydroxybenzaldehyde 4,S-diallylisothiosemicarbazone (HL) was synthesized and characterized by 1H, 13C NMR and FTIR spectroscopies. It exists in solution in two isomeric forms: cis (~25%) and trans (~75%). Six stable complexes were obtained by interaction of HL with copper(II), nickel(II), cobalt(III) and iron(III) salts: [Cu(L)Cl] (1), [Cu(L)NO3] (2), [Cu(3,4-Lut)(L)NO3] (3), [Ni(L)OAc] (4), [Co(L)2]Cl (5), [Fe(L)2]NO3 (6). The synthesized complexes have been studied by elemental analysis, FTIR, molar electrical conductivity and single crystal X-ray diffraction (6). For all compounds the antioxidant activity against cation radicals ABTS•+ was studied. All complexes and free ligand are more active than trolox that is used in medicine practice. Complex 4 (IC50=7.20µM) is the most active one. The introduction of heterocyclic amine did not improve the antioxidant activity. The introduction of S-allyl group into isothiosemicarbazone affected the activity of the synthesized substances, and in some cases the resulting complexes exhibit greater activity than complexes with isothiosemicarbazones with other S-radicals.

Heptacoordinated lanthanide(III) complexes based on 2,6-bis(1H-benzo[d]imidazol-2-yl)pyridine ligands (bbp, bmbp and bdmbp): Computational calculations, luminescent properties and cytotoxic evaluation.

Two new series of heptacoordinated obtained of hydrated lanthanide(III) nitrates (Ln3+ = La, Nd, Sm, Eu, Gd, Tb and Dy) with 2,6-bis(1H-benzo[d]imidazol-2-yl)pyridine (bbp) and 2,6-bis(5,6-dimethyl-1H-benzo[d]imidazol-2-yl)pyridine (bdmbp) were synthesized and characterized by high-resolution mass spectrometry (HR-MS), elemental analysis (EA), melting point (MP), molar electrical conductivity (MEC), effective magnetic moment (EMM) and Fourier-transform infrared spectroscopy (FT-IR). The optical properties of complexes were evaluated by ultraviolet-visible (UV–Vis) absorption and emission spectroscopy in solution. Samarium(III), europium(III), and terbium(III) complexes exhibited luminescent properties and characteristic emission bands. IR and MEC studies indicated that only two of the three nitrate groups were coordinating with the lanthanide(III) ion in a bidentate manner and confirmed the presence of the third nitrate group outside the coordination sphere. EMM analyses indicated that the metal complexes present paramagnetism, except for those of lanthanum(III). The third series of these complexes with these same trivalent lanthanide ions derived from the ligand 2,6-bis(5-methyl-1H-benzo[d]imidazol-2-yl)pyridine (bmbp) were previously reported by our research group in this same research journal (10.1016/j.molstruc.2018.03.065). Therefore, the cytotoxic activity of the three series of complexes and their ligands against NIH-3T3, J774A.1 and HeLa cell lines was studied. Only the bdmbp-based complexes exhibited moderate cytotoxic activity versus the HeLa cell line compared to the other two cell lines, while the bbp- and bmbp-derived complexes exhibited weak cytotoxic activity against all three cell lines.

Investigation of solutions of iron(II) complexes with tris(pyrazol-1-yl)methane, possessing the spin-crossover phenomenon

Using methods of static magnetic susceptibility, UV and visible spectrometry and conductometry, dimethylformamide solution of iron(II) complex with tris(pyrazol-1-yl)methane (HC(pz)3) having the composition [Fe(HC(pz)3)2]ns2 (ns = 2-naphthalene sulfonate) has been studied. In solution, as in the solid state, this compound exhibits a spin crossover of 1A1 ↔ 5T2, while in solution it is shifted to a region of lower temperatures and is sharper. It is shown that at a given concentration of 2.5 × 10−4 mol/L at 298 K, the molar electrical conductivity for the [Fe(HC(pz)3)2]ns2 complex in dimethylformamide is Λ298k = 100 ± 2 Ohm−1cm2 mol−1. Solutions of the [Fe(HC(pz)3)2]ns2 complex in a polar aprotic solvent with high dielectric permittivity are characterized by a high degree of dissociation by the type of 1,1-charging electrolyte. The dependences of the logarithm of the electrical conductivity of the studied solutions as a function of the logarithm of concentration and of 1/T are linear. The values of the electrolyte dissociation constant, pK = 2.3, and the activation energy of the charge transfer process, Ea = 5815 J/mol, are calculated. It is shown that a change in the spin state of the central atom of the complex in solution does not lead to changes in the nature of electrical conductivity and does not change Ea.

Synthesis and characterization of thiosemicarbazone metal complexes: Crystal structure, and antiproliferation activity against breast (MCF7) and lung (A549) cancers

Thiosemicarbazone compound has pronounced anticancer activity, which increases by metal ions presence. New Ni(II), Cu(II), Pd(II), and Pt(II) complexes synthesized from 2-(2,3-dihydroxy benzylidene)-N-ethylhydrazine-1-carbothioamide ligand H3L and had been characterized via NMR, GC–MS, FTIR, CHNS, UV–vis, TGA, magnetic susceptibility measurements, and molar electric conductivity. X‐ray crystallographic data and the refinement structure of thiosemicarbazide ligand indicated a clear light colorless block with the formula C10H13N3O2S, which belongs to a monoclinic system with P1 21/ c1 space group and adopts orthorhombic crystal with a = 5.1509(3) Å; b = 10.2856(6) Å; c = 11.3261(6) Å. The ligand and the metal complexes were also tested for antiproliferation activity against the MCF7 breast and A549 lung cancer cell lines. The data showed that Ni(II), Cu(II), Pd(II), and Pt(II) complexes had potent antiproliferation activity at the micromolar level. Pt(II) complex with square planar geometry exhibits the highest antiproliferation activity, while Ni(II) complex with distorted octahedral geometry showed the lowest antiproliferation activity in both cell lines.

Ancillary-Ligand-Assisted Variation in Nuclearities Leading to the Formation of Di-, Tri-, and Tetranuclear Copper(II) Complexes with Multifaceted Carboxylate Coordination Chemistry

The self-assembly of a carboxylate-based dinucleating ligand, N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H3cpdp), and copper(II) ions in the presence of various exogenous ancillary ligands results in the formation of the new dinuclear complex [Cu2(cpdp)(μ-Hisophth)]4·2H2isophth·21H2O (1), trinuclear complex [Cu3(Hcpdp)(Cl)4] (2), and tetranuclear complex [Cu4(cpdp)(μ-Hphth)(μ4-phth)(piconol)(Cl)2]·3H2O (3) (H2phth = phthalic acid; H2isophth = isophthalic acid; piconol = 2-pyridinemethanol; Cl- = chloride). In methanol-water, the reaction of H3cpdp with CuCl2·2H2O at room temperature leads to the formation of 2. On the other hand, 1 and 3 have been obtained by carrying out the reaction of H3cpdp with CuCl2·2H2O/m-C6H4(CO2Na)2 and CuCl2·2H2O/o-C6H4(CO2Na)2/piconol, respectively, in methanol-water in the presence of NaOH at ambient temperature. All three complexes have been characterized by elemental analysis, molar electrical conductivity and magnetic moment measurements, FTIR, UV-vis spectroscopy, and PXRD, including single-crystal X-ray structural analyses. The molecular structure of 1 is based on a μ-alkoxide and μ-isophthalate-bridged dimeric [Cu2] core; the structure of 2 represents a trimeric [Cu3] core in which a μ-alcohol-bridged dinuclear [Cu2] unit is exclusively coupled with a [CuCl2] species by two μ:η1:η1-syn-anti carboxylate groups forming a triangular motif; the structure of 3 embodies a tetrameric [Cu4] core, with two copper(II) ions in a distorted-octahedral coordination environment, one copper(II) ion in a distorted-trigonal-bipyramidal coordination environment, and the other copper(II) ion in a square-planar coordination environment. In fact, 2 and 3 represent rare examples of copper(II)-based multinuclear complexes showing outstanding features of rich coordination chemistry: (i) using a symmetrical dinucleating ligand, trinuclear complex 2 is generated with four- and five-coordination environments around copper(II) ions; (ii) the unsymmetrical tetranuclear complex 3 is obtained by using the same ligand with four-, five- and six-coordination environments around copper(II) ions; (iii) tetracopper(II) complex 3 shows four different bridging modes of carboxylate groups simultaneously such as μ:η2, μ:η1:η1, μ3:η2:η1:η1, and μ4:η1:η1:η1:η1, the μ4:η1:η1:η1:η1 mode of phthalate being unprecedented. The formation of these [Cu2], [Cu3], and [Cu4] complexes can be controlled by changing the exogenous ancillary ligands and pH of the reaction solutions, thus allowing an effective tuning of the self-assembly. The magnetic susceptibility measurements suggest that the copper centers in all three complexes are antiferromagnetically coupled. The thermal properties of 1-3 have been investigated by thermogravimetric and differential thermal analytical (TGA and DTA) techniques, indicating that the decomposition of all three complexes proceeds via multistep processes.

Hydrazone bimetallic complex: synthesis, characterization, in silico and biological evaluation targeting breast and lung cancer cells’ G-quadruplex DNA

Manganese complex of (N'1E,N'3E)-N'1,N'3-bis(2-hydroxybenzylidene)isophthalo-hydrazide [H4L] was designed, spectroscopically analyzed, and confirmed via GC-MS, FTIR, CHNS, UV-VIS, magnetic susceptibility measurements, and molar electric conductivity. The data confirmed the formation of ligand H4L and [Mn2(H2L)Cl]Cl.2H2O complex. Ligand H4L acts as a bi-negative hexadentate and tetra-negative hexadentate coordinating through two amide carbonyl, two azomethine, and two deprotonated OH groups. The magnetic and spectral data proposed a square-planar and a tetrahedral structure. The TGA data confirmed the final metal oxide form for the Mn ligand complex. Additionally, an in-vitro assessment of the ligand H4L confirmed its ability to control cancer cell proliferation in both breast (MCF7) and lung (A549) cancer cell lines while the Mn ligand complex possessed an anticancer effect in both cancer cells at the nano-molar level. Further, the in silico data showed four hydrogen bond interactions of the ligand with G-quadruplex DNA. This strengthens our hypothesis that the hydrazone complex acts as an anticancer agent by targeting the G-quadruplex DNA.

Synthesis, characterization and arsenate binding events of new mononuclear copper(II) complexes

Two new mononuclear copper (II) complexes [Cu(L)(H2O)Cl] (1) and [Cu(L)(H2O)(SCN)] (2) (HL = 2-[1-(2-dimethylamino-ethylimino)-ethyl]-phenol) have been synthesized and characterized in order to investigate their binding interaction with arsenate ions. Complexes 1 and 2 were synthesized by performing reaction of CuCl2·2H2O or CuCl2·2H2O/NH4SCN, respectively, with HL using Et3N as mild base in MeOH solution at room temperature, and characterized by employing a number of analytical techniques, for example, elemental analysis, molar electrical conductivity, FTIR, UV–Vis and mass spectrometry. Their structures, optimized at DFT/B3LYP/6-311G level, show that the copper atom in 1 and 2 exhibits a distorted square pyramidal geometry. In H2O/MeOH (3:1; v/v) solution, complexes 1 and 2 were examined for their binding affinity towards arsenate ions. The UV–Vis spectroscopic results specify that the arsenate group binds with 1 and 2 in 1:1 M ratio. The UV–Vis titration data were successfully utilized to calculate the binding constants of arsenate-bound Cu(II) complexes, and the values are found to be 1.723 × 104 M−1 and 2.161 × 104 M−1, corresponding to 1/AsO43− and 2/AsO43− assemblies, respectively.

Preparation and characterization of new compounds for esters and polymers derived from furfural, study of some physical applications and evaluation of their biological activity

This research includes the preparation of esters and loading of polymers through the reaction of amino acids derived from furfural with alcohols and polyvinyl alcohol by the traditional method (sublimation). 1:1 mol) and then reacts the product of Schiff's bases with the anhydride. The compounds were diagnosed using infrared spectroscopy (IR), nuclear magnetic resonance (1H, 13C-NMR), UV-Vis spectroscopy, and mass spectrometry (Mass). Laser bombardment was also performed using a scanning electron microscope (SEM) to determine the shape of the particle and whether it was a nanoparticle or not. Also, the biological activity was evaluated on four types of karma-positive and gram-negative pathogenic bacteria, which showed moderate to high inhibitory ratios and measured the molar electrical conductivity of some of them. The products were confirmed by the physical changes that occurred to them, such as color, molecular weight, and melting point.

Preparation and characterization of new compounds for schiff base derived from furfural, study of some physical applications and evaluation of their biological activity

This research includes the preparation of Schiff bases from heterocyclic compounds using furfural by the traditional method (sublimation), where mono- and diamine compounds were used. The compounds were diagnosed using FT-IR, 1H-NMR, 13C-NMR, UV-Vis Mass, and SEM to determine the shape of the molecule and whether it is nanoscale. The biological activity that showed moderate to high inhibitory ratios were also evaluated, and measured the molar electrical conductivity of some of them was.

New copper(II) cyclam complexes with aminocarboxylate co-ligands: Synthesis, characterization, and in vitro antiproliferative and antibacterial studies

Two new cationic Cu(II) complexes of cyclam (1,4,8,11-tetraazacyclotetradecane) and aminocarboxylate coligands glycine or alanine have been synthesized. The complexes were characterized by elemental analysis (C, H and N), molar electrical conductivity, magnetic susceptibility measurement at room temperature, spectral methods (UV/Vis and Fourier transform infrared), as well as by thermogravimetric (TG) and differential thermal analysis (DTA). The analytical data of the complexes show the formation of mononuclear complexes with general formula [Cu(L)cyc](ClO4)2?nH2O, A) L = glycine, n = 1.5 and B) L = alanine, n = 2.5. The tetradentate ligand cyclam was coordinated to metals through four N donors. The spectroscopic data suggested that the amino carboxylate ligands coordinated via their carboxylate ion moieties. The six- -coordinate octahedral geometry around Cu(II) in both complexes was presumed. TG-DTA analysis indicated that complex B decomposed exothermally in a single step in the range of 310?400?C. The cytotoxic activity of Cu(II) complexes and the starting ligands were tested against human cervix adenocarcinoma cell line (HeLa), human melanoma (FemX) and human colon carcinoma (LS174). The IC50 values for the Cu(II) complexes were from 48.35?82.25 ?M. Both complexes were tested for their antimicrobial activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and the yeast Candida albicans.

Viscosity and electrical conductivity of ether-functionalized ionic liquids-[C1OC2mim][OAc], [C1OC2mim][Pro] and [C2OC2mim][Pro

1-(2-Methoxyethyl)-3-methylimidazolium acetic acid ([C1OC2mim][OAc]), 1-(2-methoxyethyl)-3-methylimidazolium propionic acid ([C1OC2mim][Pro]) and 1-(2-ethoxyethyl)-3-methylimidazolium propionic acid ([C2OC2mim][Pro]) were successfully prepared by two-step synthesis method. Based on the standard addition method, the physicochemical parameters of the density, viscosity and electrical conductivity for ether-functionalized ionic liquids (ILs) were measured. The volume properties of three ether-functionalized ILs and their homologues were estimated by semi-empirical methods. According to the Eying viscosity equation, the relationship between viscosity and activation Gibbs energy for viscous flow (ΔG≠) was studied. The activation energy values for three ether-functionalized ILs were calculated by Arrhenius empirical equation. The activation energies of these ether-functionalized ILs are arranged in the following order: [C1OC2mim][Pro] (Eη = 39.17 kJ·mol−1) > [C2OC2mim][Pro] (Eη = 37.26 kJ·mol−1) > [C1OC2mim][OAc] (Eη = 37.23 kJ·mol−1). Futhermore, the Vogel-Fulcher-Tamman (VFT) equation is used to describe the relationship between viscosity (or electrical conductivity or molar electrical conductivity) and temperature, and the experimental results show that VFT equation has good general applicability.

NEAR HYDRATION OF SINGLY CHARGED MONOATOMIC IONS IN EXTREMELY DILUTED SOLUTIONS: THE EFFECT OF TEMPERATURE AND PRESSURE

The diffusion coefficient and the distance of translational displacement of Li+, Na+ K+, Cs+, Cl– and Br– ions in water at 298.15 K – 423.15 K (25 K step) and pressure from 0.0981 to 784.5 MPa (98.1 MPa step) were calculated from the literature data on limiting molar electrical conductivity. The values for these ions increase with pressure growth from 0.0981 to 98.1 MPa at 298.15 K. Further pressure increase (up to 785 MPa) leads to decrease in . Temperature growth under isobaric conditions leads to an increase in . Parameter (– ri) (deviation from the Stokes–Einstein law, ri is ion structural radius) was used as a criterion for the type of ion solvation. It is shown that Li+ and Na+ ions behave as cosmotropes, or positively solvated structure–forming ions having (– ri) > 0. The Cs+, Cl–, Br– ions behave as chaotropes, or negatively solvated structure–breaking ions having (– ri) < 0. For the K+ ion, the (– ri) deviation is alternating. At 0.0981 MPa and 298.15 K, the K+ ion is a chaotrope. But at 320 K (Tlim) parameter (– ri) = 0. It corresponds to the transition from negative to positive solvation. Above Tlim at P = const, the K+ ion is a cosmotrope. At 298.15 K and up to 98.1 MPa, the pressure causes the same change in the (– ri) deviation as the temperature. On the contrary, at 320 K and higher, the pressure affects the near hydration in the direction opposite to the temperature.

Concentration and temperature empirical relationships of the electrical conductivity of electrolyte solutions

We have considered the dependences of the specific (κ) and molar (Λ) electrical conductivity (EC) of aqueous electrolyte solutions on the molar concentration and temperature for sulfates of divalent metals (Mn, Co, Ni, Cu, Zn, Cd) in a wide concentration range at 5 – 35°C. To describe such systems we propose a modified cubic equation (MCE): κ = C∙c3k + Q∙c2k + L∙ck, where C, Q, L, k are empirical parameters, fixed parameter k = 0.5 has been considered as well. From the correlation between the calculated parameters we assume that two of them are sufficient. The maximum of specific EC (κm) and the corresponding concentration (cm) have been calculated. We also assume that the systems under study are isomorphic in the normalized coordinates (κ/κm via c/cm). For the dependences like κ = A∙cx + B∙cy it is shown that x = 1 is a good approximation over the generalized sample. Empirical dependences with y = 5/4 and y = 4/3 are also considered. It is shown that they give comparable results to MCE. The proposed approach is tested on EC data of aqueous solutions of some salts. Similar two-parameter κ(κm, cm; c) equations of other authors have been considered. In order to describe the dependence of the specific EC on temperature and concentration we propose an equation κ = (A25 + a∙θ)∙c – (B25 + b∙θ)∙c5/4, where θ is the reduced temperature and A25, a, B25 and b are empirical parameters. Also a generalized equation for the molar EC of concentrated electrolyte solutions is proposed: Λ(Λ*, Λm, cm; c), where Λ* is the effective limiting molar EC, and Λm is the molar EC at c = cm. It was found that Λ* and Λm depend linearly on temperature. The average value of the exponent is close to 1/3, which brings the generalized molar EC equation closer to the equation derived from the quasi-lattice model of electrolyte solutions.

Effect of the Structure of Imidazolium Ionic Liquids on the Electrical Conductivity and Processes of Ionic Association in Acetonitrile Solutions

A study is performed of the electrical conductivity of a number of ionic liquids based on 1-alkyl-3-methylimidazolium quaternary salts with inorganic anions in acetonitrile. The Lee–Wheaton approach is used to calculate the ion association constants Ka, limiting molar electrical conductivity (λ0), and the Gibbs energy of association (ΔG) in solutions. It is shown that the nature and size of the anion has a decisive influence on the association of the studied ionic liquids. It is found that the limiting molar electrical conductivity of bromides is lower than that of hexafluorophosphates and tetrafluoroborates.