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We report amplified near-IR (NIR) fluorescence in organic rhodamine dye nanoparticles, which can be synthesized on the basis of ion association between rhodamine-800 (Rho-800) cation and tetrakis(4...

Ion-associates formed between tetrabutylammonium ion (TBA+) and substituted nitrobenzoate ions have been extracted into nonionic surfactant micelles in an aqueous solution. The micelle extraction p...

Weak ion association equilibria between inorganic anions, ranging in charge from - 1 to -4, and symmetrical tetraalkylammonium ions, R 4 N + (R = Me, Et, Pr, Bu, n-Am), were investigated in formate buffer solutions containing a variable composition of ethanol (0-62.9% (m/m)). The individual effective mobilities of the inorganic anions in a series of tetraalkylammonium chloride solutions were measured using an ordinary silica capillary maintained at 25.0 ′ 0.1 C under a negative potential (-10 kV) and direct UV detection (λ = 220 nm). Under the stated experimental conditions, the association constants, K a s s , showed a modest increase as the amount of ethanol in the buffer was increased. The concepts of medium effect and Gibbs free energy of transfer were applied to weak ion equilibria in order to investigate changes in association constant as the ethanol content in the buffer solutions was increased. The above treatment on selected associations revealed that the increased instability of the inorganic anion in mixed ethanolic solutions is responsible for the observed increase in K a s s .

Organic nanoparticles of a carbocyanine dye (JC-1) are synthesized via ion-association between the dye cation and tetrakis(4-fluorophenyl)borate anion in the presence/absence of a neutral stabilizi...

Reactions in ion association-nonionic micellar electrokinetic chromatography have been analyzed using mobility change in capillary electrophoresis. Several quaternary ammonium ions and aromatic anions were used as pairing cations and anions, respectively, and three kinds of nonionic surfactant were used to form micelles in an aqueous solution. The apparent electrophoretic mobility of the analyte anions decreased with increasing concentrations of nonionic surfactant and/or pairing cation. The equilibrium reactions participating in this electrophoresis system are binding of anions to nonionic surfactant micelle (KB), ion association of anions with pairing cation (Kass), and distribution of the formed ion associates to the nonionic surfactant micelle (KB,IA). The equilibrium constants were determined by non-linear least-squares analyses by applying the analyses to the mobility decreases. Equilibrium constants of KB and KB,IA for monovalent anions were found to be larger than those for divalent anions, and KB...

Ion association reactions between monovalent polycyclic aromatic cations and anions have been studied through the mobility change in capillary zone electrophoresis. When the cationic reagent possessing aromatic moieties was used, isomers of aromatic anions were well resolved. Apparent electrophoretic mobility of the anions decreased with an increase in the concentration of the cationic reagent in the migrating solution; the magnitude of the decrease was large when bulkier cations were used. The ion association constants obtained by analyzing the mobility change increased with an increase in the number of aromatic rings of either the pairing cations or the anions. The ion associates formed consist of monovalent cations and anions, and the ion association constant for an ion associate formed between 1-propylbenzo[f]quinolinium ion and pyrene-1-carboxylate ion was in the magnitude of 102.74 dm3 mol-1. Such ion associability was interpreted from the contribution of the stacking of aromatic moieties in an aque...

Ion associability of some alkylammonium-type ion association reagents with the positional isomers of aromatic anions has been examined in an aqueous solution through electrophoretic mobility changes of the corresponding anions in capillary zone electrophoresis. Ion associability of the alkylammonium ions was investigated for monovalent and divalent cationic groups, considering the hydrophilicity and hydrophobicity of cationic groups and the hydration of the ionic sites. When such monovalent cationic reagents as hexylmethylammonium, hexyltrimethylammonium, and hexyltriethylammonium ions were used, the ion associability increased with an increase in the number and bulkiness of alkyl groups of the cations. On the other hand, hexylammonium ion, a primary ammonium ion, showed different behavior: Higher ion associability was obtained with aromatic anions possessing two carboxylate groups at adjacent positions. Also ion associability of the primary diammonium ions with phthalate and naphthalene-2,3-dicarboxylate...

Reaction equilibria in liquid–liquid distributions of alkali metals as crown ether complexes were clarified. The reactions and their equilibria of interest are the complex formation, the ion association of the complexes with the pairing anions in an aqueous solution, and the distribution of the formed ion associates to the organic phase. A capillary-electrophoretic method was proposed for the analysis of the equilibria in an aqueous solution. By using this method, complex formation and ion association in an aqueous solution were studied by electrophoretic mobility measurement, which was done in reactant systems consisted of alkali metal ion, dibenzo-18-crown-6, and picrate or perchlorate ion by capillary zone electrophoresis. Complex formation constants obtained agreed with the reported values obtained by the solubility measurement, and the ion association equilibria between the metal complexes and pairing anions were for the first time analyzed in this study. The reactivity of complex formation in the aq...

Ion association constants of two types of poly(vinylamine) and poly(ethylenimine) were determined from pH measurements of the polyamine/counter ion mixtures at an aqueous solution of the polymers (5 × 10−4 equiv mol dm−3). The results are discussed in terms of chemical structure (distance between reacting groups, and straight or branched chain), molecular weight, and ionic strength. The ion association at very low concentration protonated polyamines was promoted by the close location of amino groups. When the bound counter ions became close to each other, further ion association was inhibited by counter ions which had already bounded. From the colloidal titration of these polyamines, the stoichiometry could be discussed, especially under the conditions where all amino groups on the polymer are converted into ammonium ions. The results of the colloidal titration indicated that the stability constant for the ion association was drastically increasing near the equivalence point of the colloidal titration.

Interfacial ion-association adsorption of 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine (H2tpps4−) with hexadecyltrimethylammonium ion and 5,10,15,20-tetrakis(1-methyl-4-pyridinio)-21H,23H-porphine (H2tmpyp4+) with 1-hexadecanesulfonate was measured by means of a total internal reflection fluorometry at toluene/water systems. The adsorptivity of the porphyrins was negligibly small in the absence of the ionic surfactants, but it was increased by the addition of the surfactants in the 10−8—10−7 M concentration. The adsorptivity was governed by the positive or negative charge of the surface-active counter ion and its concentration, which determined the electrostatic potential of the interface. Further, it was found that zinc(II)-1,10-phenanthroline, a hydrophobic complex cation, remarkably enhanced the interfacial adsorption of [Zntpps]4− ion, but showed no positive effect on the adsorption of [Zntmpyp]4+ ion.

Protonation of tetraphenylporphyrin (TPP) and octaethylporphyrin (OEP) in toluene/acid systems was investigated by a high-speed stirring method. In toluene/sulfuric acid system, the adsorption of the diprotonated TPP and the monoprotonated OEP at the liquid–liquid interface was found, while in other acid systems including hydrochloric acid, perchloric acid, and trichloroacetic acid, the ion-association extraction of H2TPP2+ and HOEP+ was observed as well, depending on the nature of the counter anions and the concentration of the acids. An inverted correlation was suggested between the adsorption constants of the protonated porphyrins and the extraction constants of the acids with the porphyrins.

Conductivity measurements for aqueous solutions of sulfates of hexaamminecobalt(III) ([Co(NH3)6]3+) and tris(ethylenediamine)cobalt(III) ([Co(en)3]3+) complexes have been made at various temperatures from 0 to 50 °C. The conductivity data were analyzed to obtain the first ion-association constants, but could not be completely explained if the second ion association (triple-ion formation between ion pair and sulfate ion) was not taken into consideration. The ion-association constants had minimum values at particular temperatures and were significantly larger than those predicted by electrostatic ion-association theories. Excess thermodynamic functions for the first ion association over the theoretical prediction were estimated and explained by assuming the ion–ion and ion–water hydrogen bonding. The excess entropy and enthalpy changes were significantly increased with increasing temperature, while the Gibbs free energy change was little dependent on temperature; these results were attributed to the destruc...

Conductivities for aqueous solutions of alkali metal salts of tris(oxalato)chromate(III) ([Cr(ox)3]3−) were measured at various temperatures from 0 to 50 °C. Ion-association constants (KA) between the complex ion and alkali metal ions increased in the order Li+ << Na+ < K+ < Rb+ < Cs+ and had minimum values (KA(min)) at characteristic temperatures (tmin) in the observed temperature range except for the lithium ion. The appearance of minima of KA suggested the formation of contact ion pairs besides that of solvent-separated ones. The contact ion-pair formation was considered to be assisted by weak hydration of alkali metal ions and enhanced with decreasing their hydration strength. The lithium ion was presumed to form only solvent-separated ion pairs on the basis of extremely small ion-association constants. Temperature dependence of log KAfor each ion association could be represented by the equation: log KA = p(t − tmin)2 + log KA(min). A common relationship between p and tmin was found out for the ion-as...

For five kinds of triphenylmethane dyes, the rate constants of hydration and dehydration reactions, and equilibrium constants in an aqueous solution were measured by a stopped-flow method. An increase in the number of dialkylamino groups caused a decrease in the rates and the equilibrium constants of the hydration, and the more the electron-donating effect of the dialkylamino groups, the slower the hydration rate became. The more protonated quinonoids were easily converted to the corresponding alcohols. On the basis of the equilibrium constants, Malachite Green was ascertained to be the best reagent of the five dyes for ion association with heteropolyacids in an aqueous medium.

The conductivities for aqueous solutions of the chloride, bromide, iodide, nitrate, and perchlorate of the tris(ethylendiamine)cobalt(III) complex, [Co(en3)]3+, were measured with varying temperatures from 0 to 50 °C. The ion-association constants (KA) of the complex ion with the anions had minimum values at temperatures (tmin) characteristic of the salts. The values of tmin increased in the order Cl− < Br− < I− < NO3− < ClO4−. The order in magnitude of KA at 25 °C was ClO4− < NO3− < I− < Cl− < Br−, but was somewhat dependent on the temperature. Both the KA and tmin values for the halides of [Co(en)3]3+ were larger than those of the hexaamminecobalt(III) complex, [Co(NH3)6]3+; the difference in KA was greatest for the iodide. The entropy and enthalpy changes in the ion association of [Co(en)3]3+ with the halide ions were smaller than those of [Co(NH3)6]3+. These results suggested that the hydration of [Co(en)3]3+ was relatively weak and its hydration water molecules in the vicinity of the methylene groups...

モリブドリン酸イオン(PMo)とマラカイトグリーン(MG+)は酸性溶液中で反応し発色する。この反応はイオン会合体(MG++-PMo)形成反応であり,生成反応は次のように表される.HMG2++H3PMo12O40→(MG+)H2PMo12O40+2H+ただしHMG2+はMG+のプロトン付加体を表し黄色(λmax=446nm)であるが,イオン会合体になるとMG++の緑青色(λmax=650nm)になる。MG+はPMoの生成を促進する役割も大きいことがわかった。有機溶媒はPMoの生成促進のみならず,MG+-PMoの生成も促進することがわかった。陰イオン界面活性剤は反応を減速させるが,フローインジェクション分析におけるベースラインのドリフト抑制に寄与することがわかった。反応促進剤とベースライン抑制剤の使用により,短い反応コイルで数ppbの低濃度域まで良好な直線関係を示すFIAシステムを確立することができた。

The ion associations of [Co(NH3)6]3+, [Cr(en)3]3+(en=ethylenediamine), lel3-[Cr(R-chxn)3]3+ lel3=lel,lel,lel-, and chxn=trans-1,2-cyclohexanediamine), [Co(bpy)3]3+ (bpy=2,2′-bipyridine), [Co(phen)3]3+(phen=1,10-phenanthroline), and [Cr(phen)3]3+ with Cl−, SO42−, CH3SO3−, C6H5SO3−, (CH2SO3)22−, and m-C6H4(SO3)22− were investigated at 25°C by means of conductivity measurements of aqueous mixed electrolyte solutions with a stoichiometrically constant ionic strength of 0.01 mol dm−3. The ion-association constants thus obtained were compared with each other and also with those estimated by the use of electrostatic theories of ion association. Some specific interactions besides such usual electrostatic ones were found to play important roles in the ion associations of SO42− with [Co(NH3)6]3+ and [Cr(en)3]3+, in those of C6H5SO3− and m-C6H4(SO3)22− with [Co(phen)3]3+, [Cr(phen)3]3+, and [Co(bpy)3]3+, and in those of SO42−, C6H5SO3−, and m-C6H4(SO3)22− with lel3-[Cr(R-chxn)3]3+. The specific interactions existing...

The molar conductivity of manganese(II) sulfate, MnSC4, in aqueous solution was measured in a temperature range of 10–45°C. The acquired data were analyzed by the Quint-Viallard equation, and the resulting ion association constant, KA, was used in the Bjerrum equation to determine the contact ion size, RB. The limiting ionic molar conductivity λ0 (1/2 Mn2+) for the manganese ion at 15, 25, 35, and 45°C are 40.8, 53.1, 65.2, and 79.8 S cm2 mol−1, respectively. The resulting thermodynamic properties for the ion association reaction are: ΔG°298=−13.5 kJ mol−1, ΔH°=7.91 kJ mol−1, and ΔS°298=74.1 JK−1 mol−1.

We demonstrate a simple and versatile method for preparing ion-based organic nanoparticles in aqueous solution. Ion association between a cationic pseudoisocyanine dye and a tetraphenylborate anion...

Sodium hyaluonate (NaHA) and Methylene Blue (MB) formed a complex through charge transfer (CT) interaction or ion association in aqueous solution. Irradiation of the complex using a 313-nm light under argon caused degradation of NaHA. The mechanism proposed on the basis of the effect of excitation wavelength and oxygen, and by comparison with the degradation of NaHA using Rose Bengal (RB) and TiO2, was that photoinduced electron transfer from NaHA to upper excited state MB initiated the degradation.

Formation of ion associate in an aqueous solution has been examined using some aromatic divalent anions and symmetric quaternary ammonium ions through the mobility change of capillary electrophoresis. The electrophoretic mobilities of the anions decreased with an increase in the concentrations of bulky quaternary ammonium ions. Ion association constants (Kass) of 2,6-naphthalenedicarboxylate, 1,5-naphthalenedisulfonate, and 2,6-naphthalenedisulfonate with tetrabutylammonium ion as a pairing ion were determined to be 101.4, 101.4, and 101.3, respectively, while mobility changes of 2,3-naphthalenedicarboxylate and phthalate ions were slight. Several quaternary ammonium ions were examined. The results suggest that the bulkiness of the pairing cations is related to the ion association in aqueous solutions.

Ion-association adsorption of water-soluble, surface-inactive anionic and cationic porphyrins with the oppositely charged surfactants was observed at toluene/water interface by means of a total internal reflection fluorometry. Water-soluble zinc(II)-porphyrin was also adsorved at the liquid/liquid interface with a hydrophobic zinc(II)-1,10-phenanthroline complex ion.

The results of previous studies on ion association were re-examined. The formation constants of inner-sphere ion-pairs were obtained for several bivalent-metal sulfates by estimating the formation constants of outer-sphere ion-pairs with the help of the ion-association theory. The interactions between metal and sulfate ions were discussed by comparing these results.

A computer program has been developed for the simultaneous determination of the first- and second-ion-association constants from spectroscopic(NMR, UV, or CD) or conductance measurements, and applied to the system, acetylacetonatobis(ethylenediamine)cobalt(III) and chloride ions in dimethylsulfoxide.

The electric conductivities of potassium nitrate and potassium perchlorate in water have been measured at eleven temperatures from 0 to 50 °C and analyzed in order to obtain the ion-association constants and the limiting molar conductivities of these salts. It was found that the observed ion-association constants have a minimum value at 30 °C for KNO3 and at 36 °C for KClO4. Such a characteristic temperature dependence was considered to be due to the presence of specific short-range interactions within contact ion pairs, although the weak hydration of the ions seemed to help the formation of the contact ion pairs. The experimental standard enthalpies and entropies of ion association were discussed in comparison with the theoretical ones. The limiting molar conductivities of NO3− and ClO4− at each temperature were also evaluated and expressed as cubic equations of the temperature.

Conductance data are reported for dilute solutions of pentaamminenitrocobalt(III) sulfate, [Co(NO2)(NH3)5]SO4, and tris(1,10-phenanthroline)iron(II) sulfate, [Fe(phen)3]SO4 in water–ethylene glycol mixed solvents at 25 °C. The conductance data were analyzed in terms of the 1957 Fuoss-Onsager and Fuoss-Hsia equations. While the application of the 1957 Fuoss-Onsager equation to [Fe(phen)3]SO4 data suggested a complete dissociation of the salt over the entire range of solvent compositions, the Fuoss-Hsia equation fitted the data better and yielded KA values which are in accord with the ion association theories. [Co(NO2)(NH3)5]SO4 had a higher association constant in the range of solvent composition studied (0 to 40% ethylene glycol) than the predictions of the ion association theories.

The ion association constants and the molar CD’s were determined for the ion pairs, Λ- AND Δ-[Co(en)3]3+ with L- and meso-tartrates, by utilizing CD measurements. The structures of these ion pairs were consistently interpreted in terms of the above two parameters. Furthermore, the results obtained here were compared with the chromatographic behaviors of these systems.

The conductance of tris(1,10-phenanthroline)iron(II) sulfate, Fe(phen)3SO4, and chloride, Fe(phen)3Cl2, has been measured in water-methanol mixed solvent at 25 °C. The data of the sulfate could be explained by means of the Fuoss-Onsager equation (1957) and the Fuoss-Onsager-Skinner equation (1965) on the assumption that the salt is completely dissociated in the entire composition range of the solvent system. Application of the Fuoss-Hsia equation which contains a c3⁄2 term gave association constants increasing from a value of KA=40 in water to KA=3900 in methanol. The logKA vs. 1/D plot is in good agreement with ion association theoreies. The limiting equivalent conductance of Fe(phen)32+ ion was estimated to be 34.3 in water and 62.3 in methanol.

Simple and mixed aqueous solutions of copper, magnesium, calcium, manganese, and zinc sulfates were spectrophotometrically studied in order to obtain the ion-association constants of the divalent metal ions with the sulfate ion. The ion-association constant of copper sulfate was obtained from the measured absorbances of copper sulfate solutions at 250 nm as a function of the closest distance of approach of ions. For the other metal sulfates which show a negligible absorption at 250 nm, absorbances were measured on the mixed solutions with copper sulfate, and the results were analyzed by the use of the results on copper sulfate in order to obtain the ion-association constants. The best values of the ion-association constant and the closest distance of approach were determined for each metal sulfate with the help of the theory of ion association. The results were compared with those obtained from the measurements of osmotic coefficients and electric conductivities. The numerical results are summarized in Ta...

The substitution reaction [Co(NH3)5(H2O)]3++hexacyclen·3H2SO4+6base+charcoal gives mer-[Co(hexacyclen)]3+ as the major product, and the equilibrium proportion of the fac isomer is

The electric conductivities of aqueous solutions of the diastereoisomeric salts, Δ(−)589-cis-[Co(NO2)2(en)2]Δ(+)589-[Co(mal)2(en)] and Λ(+)589-cis-[Co(NO2)2(en)2]Δ(+)589-[Co(mal)2(en)](en=ethylenediamine and mal=malonate ion), have been measured at several temperatures from 15 to 35 °C. From the analysis of the conductivity data using the Pitts equation, it was found that the Δ- or Λ-cis-[Co(NO2)2(en)2]+ and Δ-[Co(mal)2(en)]− ions are appreciably associated in spite of the large monovalent ions and that the ion association is almost nonstereoselective and is endothermic in contrast to the exothermic ion association between Δ- or Λ-cis-[Co(NO2)2(en)2]+ and Δ-[Co(edta)]− (edta=ethylenediaminetetraacetate ion). By considering the obtained values of thermodynamic parameters of ion association and the significantly large Stokes radius of Δ-[Co(mal)2(en)]− compared to the effective radius estimated from its partial molar volume, this complex anion was presumed to have two hydration water molecules and to releas...

Electric conductivities of the diastereoisomeric salts, Δ(−)589-[Co(NO2)2(en)2]Δ(+)546-[Co(edta)] and Λ-(+)589-[Co(NO2)2(en)2]Δ(+)546-[Co(edta)], were measured in water at 15, 25, and 35 °C. Results were analyzed in terms of the conductivity equations of Fuoss-Hsia and Pitts. The obtained values of the ion-association constant are large and decrease with increasing temperature. The results can not be entirely explained by the electrostatic theories of ion association and suggest the formation of contact ion pairs, attributable to the existence of interactions other than simple electrostatic ones between the complex ions. No appreciable difference is found in the obtained thermodynamic parameters of ion association between the two salts. Ion–solvent interactions and effective sizes of the dissolved complex ions are also discussed in connection with the estimation of the closest distance of approach of the ions.

The sorption and extraction of heavy metal thiocyanate complexes from an aqueous solution were studied for a cellulose acetate polymer and conventional organic solvents. The ease of metal sorption to solid cellulose acetate correlated well with the ease of metal extraction to liquid glycerol triacetate. The distribution behavior of ammonium thiocyanatozincate complexes was studied in detail and compared among cellulose acetate, isobutyl methyl ketone, and glycerol triacetate. The chemical processes involved in the metal distribution to the organic phase were found to be essentially the same for these three media. Thus, cellulose acetate was conveniently considered a polymer solvent. The results were discussed in relation to metalselective hyperfiltration through cellulose acetate membranes.

The classical Debye-Huckel theory of strong electrolyte solutions was re-examined in order to explain ion association. Regarding a symmetrical electrolyte in very dilute solutions, a more precise expression was derived for excess chemical potential due to electrostatic ion-ion interactions. This expression has, in addition to the Debye-Huckel term, a supplementary term resulting from a more proper account of the energy of the interactions of ions existing near each other. If the concept of ion association is taken as a complement of the Debye-Huckel theory, the contribution to the chemical potential of the electrolyte from ion association should correspond to the supplementary term. The following equation was thus obtained for the ion-association constant: K=(8πNa^3/1000) \overset∞\undersetn=1∑b^2n+2/[(2n+2)! (2n-1)] This equation is in agreement with that derived by Ebeling on the basis of the cluster theory and has an asymptotic representation (at b→∞) in common with Bjerrum’s. For practical b values, t...

The interfacial adsorptivity of an iron(II)–4,7-diphenyl-1,10-phenanthroline (DPP) complex in chloroform/aqueous salt solution systems was investigated by means of a high-speed stirring method and interfacial tension measurements. The interfacial spectra observed in the stirred system suggested that the adsorbed species at the interface is the tris-DPP complex. A minor effect of the anion concentration on the adsorptivity suggested that the tris-complex adsorbed as an ion-pair in a 0.1 M anion concentration. The interfacial adsorption of the ion-pair under stirring was analyzed by the Langmuir isotherm. The adsorptivity increased, depending on the counter ions, in the order ClO4−

The current-potential curves of some substitution-inert complex ions are affected by the change in the composition of the supporting electrolyte. The change in the one-electron reduction wave of hexaquochromium(III) ions with the increase in the concentration of sodium perchlorate and sodium iodide is analyzed in terms of the effect of the structure of the electrical double layer. The addition of sodium sulfate at a constant ionic strength of 0.1 shifts the half-wave potentials of hexaquochromium(III), hexamminechromium(III) and hexamminecobalt(III) ions to more negative potentials. In the case of hexamminecobalt(III), the shift is much greater than in the cases of the former two complex ions. These phenomena are interpreted to be due to the effects of the double layer structure and of the ion association.

Thermodynamic equilibrium constants for the ion-association in aqueous solutions of magnesium and nickel sulfates were determined by electrical conductivity measurements at various temperatures between 0°C and 45°C. The standard Gibbs energy and the enthalpy and entropy for the reaction M2++SO42−\ightleftharpoonsM2+·SO42− (M: Mg or Ni) were then calculated from the temperature-dependence of the ion-association constants. The values obtained are as follows: ΔG°298=−2.91 kcal mol−1, ΔH°=2.04 kcal mol−1, and ΔS°298=16.6 cal deg−1 mol−1 for Mg2·SO42−; and ΔG°298=−3.10 kcal mol−1, ΔH°=1.27 kcal mol−1, and ΔS°298=14.7 cal deg−1 mol−1 for Ni2+·SO42−.

The Debye–Huckel theory of electrolyte solutions was re-examined to explain ion association. At infinite dilution, a more exact expression was derived for the chemical potential of a symmetrical electrolyte, and was related to the ion-association constant. From measured vapor pressure depressions of electrolyte solutions, log K values were obtained to be 2.11, 2.15, 2.26, and 1.67 for MgSO4, CaSO4, MnSO4, and [Ru(phen)3]SO4, respectively.

The conductance behavior of some hexa-amminecobalt(III) complexes in dilute aqueous solutions at 25°C was studied in association with the ion-pair formation of hexa-amminecobalt(III) ions. The equivalent conductivities were analyzed according to the Onsager theory, and the thermodynamic formation constants, K, of the ion-pairs, [Co(NH3)6]3+·AzA−, were determined. The logK values obtained are 1.40 (perchlorate), 1.63 (nitrate), 1.65 (bromide), 1.38 (iodide), and 3.25 (oxalate). These values were compared with the formation constants calculated from the spectroscopic data, and discussed in terms of Bjerrum’s theory on ion association.

The ion association between trioxalatocobaltate(III) anion and uni-, bi- and tervalent cations in aqueous solutions has been studied by polarographic and ultraviolet, visible and infrared spectroscopic methods. The association constants have been obtained by the measurement of the polarographic diffusion current of trioxalatocobaltate(III) ions in the presence of varied concentrations of cations at ionic strength 0.1 (NH4NO3) and 25°C. The influence of ammonium ion was taken into consideration in the treatment of polarographic data. The values obtained are 7.9 for (CH3)4N+[Co(ox)3]3−, 3.7±0.4 for (C2H5)4N+[Co(ox)3]3−, 22±1 for Na+[Co(ox)3]3−, 56±6 for Mg2+[Co-(ox)3]3−, 55±4 for Ca2+[Co(ox)3]3−, 53±3 for Sr2+[Co(ox)3]3−, 55±7 for Ba2+[Co(ox)3]3− and 118±17 for Al3+[Co(ox)3]3−. The association constant of NH4+[Co(ox)3]3− was determined by the conductivity measurement to be 33.6 (logK=1.53) at zero ionic strength. No change was observed in the visible, the ultraviolet and the infrared absorption spectra of t...

The dielectric constant and the equivalent conductivity of solutions of hexadecyl and octadecylamine hydrochloride have been measured at the frequencies of 2 Mc./ sec. and 30 Mc./sec. The dielectric constant of the solutions shows a considerable increase beyond the concentration for micelle formation. The dielectric constant and the equivalent conductivity of the solutions of these amine salts in aqueous ethanol of various concentrations have been measured. The rise of the dielectric constant is diminished with increasing concentration of ethanol. The effect of solubilization of benzene on the dielectric constant of the solutions has been investigated. The relative increase in the dielectric constant is reduced with increasing amount of solubilized benzene. From these experimental results, it is concluded that the rise of the dielectric constant of the aqueous solutions is mainly due to Debye-Falkenhagen’s effect.

The ion association of hexacyanoferrate(III) and hexacyanoferrate(II) anions with univalent or bivalent cations in aqueous solutions has been studied by the measurement of the infrared absorption band due to the C≡N stretching vibrations. All the solutions measured in which ion-pairs with hexacyanoferrates(III) predominated gave an absorption maximum at 2121 cm−1, and those in which ion-pairs with hexacyanoferrates(II) predominated, at 2020 cm−1, although hexacyanoferrates(III) and hexacyanoferrates(II) of potassium and alkaline earth metals gave different spectra from each other in solid state. No difference in absorption band obtained with different solutions was supported by the distance between two ions in ion-pair, which was estimated from the structures of hexacyanoferrate(III) and hexacyanoferrate(II) ions and the closest approach of the ion-pair; this indicates that there is no direct interaction between the complex anion and the cation, but one or more water molecules interpose between the two ions.

The extraction of aluminum(III)-Alizarin Red S(ARS)chelate with methyl isobutyl ketone (MIBK) in the presence of 1, 3-dibhenylguanidinium(DPG) salt has been investigated spectro-photometrically. The extracted species has an absorption maximum at abeut 525 nm, with a constant abserbance in the pH range from 5.5 to 5.9. For the absorbance of the association complex under the optimum conditions of pH, reagent concentrations and shaking time, Beer's gaw is obeyed up to 1.5 10"5 mo/1 aluminum in aqueous phase. The molar absorptivity is 2.90 104l/mol cm at 525 nm. lt is found that the 1:2 aluminum-ARS chelate anion formS ion association complex of 1:2 molar ratio with DPG cation, and the complex is extracted from aqueous phase into organic phase.

Ion association at the surface of a micelle is reinterpreted by considering that counter ions are bound by an electrostatic attraction with a spherical shell which is formed by the aggregation of the polar heads of amphiphilic molecules. It was found that the degree of ion association increased slightly with the increase in the aggregation number of amphiphilic molecules.

By analyzing the intensity changes in the circular dichroism spectra, the association constants of the Λ-and Δ-[Co(en)3]3+ ions with the bis(μ-(−)589-2,3-dimethyltartrato)diantimonate(III) ion were determined to be 58.4±1.9 and 38.6±0.4 respectively in H2O (mol−1 dm3 at 25°C and μ=0.1 (NaClO4)). Based on these data together with the chromatographic data, the enantioselective association mode was discussed.

The conductometric study of bis(2,4-pentanedionato)(diamine) cobalt(III) bromides in nitrobenzene at 25 °C indicated that the ion association constant of the chelate salts increases in the order, [Co(acac)2(N,N,N′,N′-tmen)]Br

The ion-association equilibrium of tetrabutylammonium chloride, bromide, and iodide in the titled solvents has been investigated by solvent extraction at 298 K. In each solvent the association constants have been found to be of similar magnitude among these three salts. This is explained in terms of the larger degree of hydration in the smaller anions. The influence of coextracted water on the equilibrium is discussed.

From the temperature dependence of the ion-association constants between K+ and SO42− at 0 to 50 °C, the contact ion-pair formation and short-range interactions are discussed while considering the hydration of the anion. The limiting molar conductivities of SO42− are expressed as a cubic equation of the temperature.

An empirical rule is presented for the elution order of [CoN6]3+-type complexes in chromatography on SP-Sephadex columns. The relative elution rates have been correlated with the number and the kind of the octahedral faces of the complex on which ion association with a phosphate ion occurs.

The solution CD spectra of (−)546-Δ(lel3)-[Co(R,R-ptn)3]3+ ion were found to be seriously affected by its counter ions. The CD change may be due to ion association between the complex and the counter ions.