High quality micro-Raman spectra of the LiClO4 droplet with mass of nanogram scale were obtained at various concentrations from dilute to supersaturated state. From component band analysis of the v1-ClO4^- band, four ...High quality micro-Raman spectra of the LiClO4 droplet with mass of nanogram scale were obtained at various concentrations from dilute to supersaturated state. From component band analysis of the v1-ClO4^- band, four peaks at 933.3, 936.8, 942.1 and 950.7 cm^-1 were identified and assigned to free solvated perchlorate anion, solvent-shared ion pair, contact ion pair and com- plex ion aggregates, respectively. As expected, the signature of free solvated CIO4 ion was observed to decrease in intensity with the increase in concentration. The intensity of the signature from solvent-shared ion pair was observed to rise with in- crease in concentration from 1.8 mol/kg to 5.0 mol/kg before decreasing as the concentration was further increased to 5.6 mol/kg. Signatures of contact ion pair and of complex ion aggregates were shown to increase as the concentration was enhanced. Based upon the Eigen mechanism, we show that three association equilibria can be used to describe the transfor- mations between free solvated perchlorate anion, solvent-shared ion pair, contact ion pair and complex ion aggregates. The overall association constant, K, and the stepwise association constants Ki （i = 1 to 3） in the Eigen mechanism were determined separately with values of 0.025 ± 0.003, 0.023 ± 0.002, 0.068 ± 0.033 and 0.686 ± 0.174. Based on these constants, the electronic performance can be reasonably predicted by the optimum choice of electrolyte concentrations.展开更多
This paper reports a classical molecular dynamics study of the potential of mean forces(PMFs),association constants,microstructures K^+-Cl^- ion pair in supercritical fluids.The constrained MD method is used to derive...This paper reports a classical molecular dynamics study of the potential of mean forces(PMFs),association constants,microstructures K^+-Cl^- ion pair in supercritical fluids.The constrained MD method is used to derive the PMFs of K^+-Cl^- ion pair from 673 to 1273 K in low-density water(0.10-0.60 g/cm).The PMF results show that the contact ion-pair(CIP) state is the one most energetically favored for a K^+-Cl^- ion pair.The association constants of the K^+-Cl^- ion pair are calculated from the PMFs,indicating that the K^+-Cl^- ion pair is thermodynamically stable.It gets more stable as T increases or water density decreases.The microstructures of the K^+-Cl^- ion pair in the CIP and solvent-shared ion-pair states are characterized in detail.Moreover,we explore the structures and stabilities of the KCl-Au(I)/Cu(I) complexes by using quantum mechanical calculations.The results reveal that these complexes can remain stable for T up to1273 K,which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.展开更多
Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties o...Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties of Cs-Cl and Cs-F ion pairs in hydrothermal fluids. The association constants(log_(10)K_(A)(m)) under a wide range of temperature(i.e. 298–1273 K) and fluid density(i.e. 0.1–1.0 g/cm^(3)) were derived from the potential of mean force(PMF) curves. The results indicate that CsCl and Cs-F ion pairs have similar stabilities. This is different from other alkali metal cations(e.g., Li^(+), Na^(+), and K^(+)), which prefer binding with F over Cl. The stabilities of Cs-Cl and Cs-F ion pairs increase with increasing temperature(except for the fluid density ≤ 0.1 g/cm^(3)) or decreasing fluid density, which is similar to other alkali halide ion pairs. Comparisons among the stabilities of CsCl/F and other alkali halide ion pairs indicate that the Li–F ion pair has the highest stability in hydrothermal fluids.展开更多
Introduction Magnesium sulfate is an archetypal 2-2 salt that plays a central role in defining the characteristics of higher valent electrolyte solutions and its solution has been widely used to test various theories...Introduction Magnesium sulfate is an archetypal 2-2 salt that plays a central role in defining the characteristics of higher valent electrolyte solutions and its solution has been widely used to test various theories of strong electrolyte behavior and to develop models of ion association in solution. Up to now, the ion pairs of magnesium sulfate in an aqueous solution have been widely investigated by using different experimental techniques, such as conductometry , cryoscopy potentiometry solubility and Raman spectrometry. However, to our knowledge, no measurement of the standard association constant of the ion pairs, [ MgSO4 ]^0 in a glucosewater mixed solvent is available.展开更多
An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The ...An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.展开更多
Extraction of sulphonated dyes through supramolecular interaction with calix[4]arene derivatives is being presented here. The selectivity of calixarene derivatives namely piperidine derivative of calix[4]arene (calix-...Extraction of sulphonated dyes through supramolecular interaction with calix[4]arene derivatives is being presented here. The selectivity of calixarene derivatives namely piperidine derivative of calix[4]arene (calix-1), 1-methyl piperazine derivative of calix[4]arene (calix-2), and di-methyl amine derivative of calix[4]arene (calix-3) were evaluated initially against reactive red 2 (RR-2), acid black (AB), reactive blue 19 (B-19) and synthetic dye (D-2) by liquid-liquid extraction experiment. The results showed that the above three calixarenes possess excellent complexation abilities toward the selected dyes. The stoichiometric ratio for the calixarene derivatives and dyes was estimated through Job’s plot, whereas Hildebrand-Benesi equation was used to calculate formation constant (K<sub>s</sub>) and molar absorptivity (Δε) of complexes. The binding association (K<sub>a</sub>) and dissociation (K<sub>d</sub>) constants were calculated by Scatchard plot additionally to further support the complexation data obtained from Hildebrand-Benesi equation. Conversely association constants from, both Hildebrand-Benesi equation and Scatchard plot i.e. K<sub>s</sub> and K<sub>a</sub> favor strong binding interaction between calix-1: D-2, calix-2: B-19, and calix-3: AB complexes. Thus present study adeptly supports the complexation of calixarene derivatives for sulfonated dyes.展开更多
The technique of supported liquid membranes was used to achieve the facilitated transport of Cr(III) ions, using tow amphiphilic carriers, the methyl cholate and resorcinarene. For prepared SLMs, toluene as organic ph...The technique of supported liquid membranes was used to achieve the facilitated transport of Cr(III) ions, using tow amphiphilic carriers, the methyl cholate and resorcinarene. For prepared SLMs, toluene as organic phase and film of polyvinylidene difluoride, as hydrophobic polymer support with 100 μm in thickness and 0.45 μm as the diameter of the pores. The macroscopic parameters (P and J0) on the transport of these ions were determined for different medium temperatures. For these different environments, the prepared SLMs were highly permeable and a clear evolution of these parameters was observed. The parameter J0 depended on the temperature according to the Arrhenius equation. The activation parameters, Ea, ΔH≠ and ΔS≠, for the transition state on the reaction of complex formation (ST) , were determined. To explain these results for this phenomenon, and achieve a better extraction of the substrate, a model based on the substrate complexation by the carrier and the diffusion of the formed complex (ST) was developed. The experimental results verify this model and determine the microscopic parameters (Kass and D*). These studies show that these parameters Kass and D* are specific to facilitated transport of Cr(III) ions by each of the carriers and they are changing significantly with temperature.展开更多
Both HA-CdS and HB-CdS (Hys-CdS, Hys represents HA, HB) complex systems were established according to the dynamics of heterogeneous electron-transfer process μ = Es/s+-ECB <0. In these systems, the electron transf...Both HA-CdS and HB-CdS (Hys-CdS, Hys represents HA, HB) complex systems were established according to the dynamics of heterogeneous electron-transfer process μ = Es/s+-ECB <0. In these systems, the electron transferring from 1Hys* to conduction band ofCdS is feasible. Determined from the fluorescence quenching, the apparent association constants (Kapp) between Hypocrellin A(HA), Hypocrellin B (HB) and CdS sol. were about 940 (mol/L)-1, 934 (mol/L)-1, respectively. Fluorescence lifetime measurements gave the rate constant for the electron transfer process from 1HA*, 1HB* into conduction band of CdS semiconductor as 5.16×109 s-1, 5.10×109 s-1, respectively. TEMPO (2,2,6,6-tetramethy-1-piperdinyloxy), a stable nitroxide radical, was used in the kinetic study of the reduction reaction taking place on the surface of a CdS colloidal semiconductor, kinetics equation of the reaction was determined with the electron paramagnetic resonance (EPR) method, and the reaction order of TEMPO is zero. When Hys were added, the rate of EPR increased greatly. By comparing rate constants, the Hys-CdS systems were revealed to be about 350 times more efficient than CdS sol. alone in the photoreduction of TEMPO under visible light. It suggests that Hys can be used as efficient sensitizers of a colloidal semiconductor in the application of solar energy.展开更多
基金supported by the National Natural Science Foundation of (41175119 20933001 and 20873006)+3 种基金the National Key Program for Basic Research of China (2009CB220100) the 111 Project B07012the Trans-Century Training Program Foundation for the Talentsalso supported by a grant-in-aid for Youth Innovation Fund from Central South University of Forestry and Technology (104︱0261)
文摘High quality micro-Raman spectra of the LiClO4 droplet with mass of nanogram scale were obtained at various concentrations from dilute to supersaturated state. From component band analysis of the v1-ClO4^- band, four peaks at 933.3, 936.8, 942.1 and 950.7 cm^-1 were identified and assigned to free solvated perchlorate anion, solvent-shared ion pair, contact ion pair and com- plex ion aggregates, respectively. As expected, the signature of free solvated CIO4 ion was observed to decrease in intensity with the increase in concentration. The intensity of the signature from solvent-shared ion pair was observed to rise with in- crease in concentration from 1.8 mol/kg to 5.0 mol/kg before decreasing as the concentration was further increased to 5.6 mol/kg. Signatures of contact ion pair and of complex ion aggregates were shown to increase as the concentration was enhanced. Based upon the Eigen mechanism, we show that three association equilibria can be used to describe the transfor- mations between free solvated perchlorate anion, solvent-shared ion pair, contact ion pair and complex ion aggregates. The overall association constant, K, and the stepwise association constants Ki （i = 1 to 3） in the Eigen mechanism were determined separately with values of 0.025 ± 0.003, 0.023 ± 0.002, 0.068 ± 0.033 and 0.686 ± 0.174. Based on these constants, the electronic performance can be reasonably predicted by the optimum choice of electrolyte concentrations.
基金National Science Foundation of China(Nos.41222015,41273074,41425009,and 41572027)Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(the second phase)+1 种基金the Foundation for the Author of National Excellent Doctoral Dissertation of P.R.China (No.201228)Newton International Fellowship Program and the financial support from the State Key Laboratory at Nanjing University
文摘This paper reports a classical molecular dynamics study of the potential of mean forces(PMFs),association constants,microstructures K^+-Cl^- ion pair in supercritical fluids.The constrained MD method is used to derive the PMFs of K^+-Cl^- ion pair from 673 to 1273 K in low-density water(0.10-0.60 g/cm).The PMF results show that the contact ion-pair(CIP) state is the one most energetically favored for a K^+-Cl^- ion pair.The association constants of the K^+-Cl^- ion pair are calculated from the PMFs,indicating that the K^+-Cl^- ion pair is thermodynamically stable.It gets more stable as T increases or water density decreases.The microstructures of the K^+-Cl^- ion pair in the CIP and solvent-shared ion-pair states are characterized in detail.Moreover,we explore the structures and stabilities of the KCl-Au(I)/Cu(I) complexes by using quantum mechanical calculations.The results reveal that these complexes can remain stable for T up to1273 K,which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.
基金supported by the National Natural Science Foundation of China (Nos 92062213,91855209,42125202 and 41872041)the financial support from the State Key Laboratory for Mineral Deposits Research at Nanjing University。
文摘Magmatic-hydrothermal processes play an important role in the transport, enrichment, and mineralization of cesium. In this study, classical molecular dynamics simulations were performed to investigate the properties of Cs-Cl and Cs-F ion pairs in hydrothermal fluids. The association constants(log_(10)K_(A)(m)) under a wide range of temperature(i.e. 298–1273 K) and fluid density(i.e. 0.1–1.0 g/cm^(3)) were derived from the potential of mean force(PMF) curves. The results indicate that CsCl and Cs-F ion pairs have similar stabilities. This is different from other alkali metal cations(e.g., Li^(+), Na^(+), and K^(+)), which prefer binding with F over Cl. The stabilities of Cs-Cl and Cs-F ion pairs increase with increasing temperature(except for the fluid density ≤ 0.1 g/cm^(3)) or decreasing fluid density, which is similar to other alkali halide ion pairs. Comparisons among the stabilities of CsCl/F and other alkali halide ion pairs indicate that the Li–F ion pair has the highest stability in hydrothermal fluids.
文摘Introduction Magnesium sulfate is an archetypal 2-2 salt that plays a central role in defining the characteristics of higher valent electrolyte solutions and its solution has been widely used to test various theories of strong electrolyte behavior and to develop models of ion association in solution. Up to now, the ion pairs of magnesium sulfate in an aqueous solution have been widely investigated by using different experimental techniques, such as conductometry , cryoscopy potentiometry solubility and Raman spectrometry. However, to our knowledge, no measurement of the standard association constant of the ion pairs, [ MgSO4 ]^0 in a glucosewater mixed solvent is available.
文摘An equation for determining the equilibrium association constant (KA) of cyclodextrin inclusion complex with fluorescence anisotropy is derived and used to determine KA of pyrene-B-cyclodextrin inclusion complex. The existing forms of cyclodextrin inclusion complex in solution, the interaction type of host with guest, and the possibility of application of B-cyclodextrin in the analysis of metal ions using naphthalene derivative as a ligand are discussed based on the equation derived along with the curve of fluorescence anisotropy versus cyclodextrin concentration of guest/cyclodextrin system.
文摘Extraction of sulphonated dyes through supramolecular interaction with calix[4]arene derivatives is being presented here. The selectivity of calixarene derivatives namely piperidine derivative of calix[4]arene (calix-1), 1-methyl piperazine derivative of calix[4]arene (calix-2), and di-methyl amine derivative of calix[4]arene (calix-3) were evaluated initially against reactive red 2 (RR-2), acid black (AB), reactive blue 19 (B-19) and synthetic dye (D-2) by liquid-liquid extraction experiment. The results showed that the above three calixarenes possess excellent complexation abilities toward the selected dyes. The stoichiometric ratio for the calixarene derivatives and dyes was estimated through Job’s plot, whereas Hildebrand-Benesi equation was used to calculate formation constant (K<sub>s</sub>) and molar absorptivity (Δε) of complexes. The binding association (K<sub>a</sub>) and dissociation (K<sub>d</sub>) constants were calculated by Scatchard plot additionally to further support the complexation data obtained from Hildebrand-Benesi equation. Conversely association constants from, both Hildebrand-Benesi equation and Scatchard plot i.e. K<sub>s</sub> and K<sub>a</sub> favor strong binding interaction between calix-1: D-2, calix-2: B-19, and calix-3: AB complexes. Thus present study adeptly supports the complexation of calixarene derivatives for sulfonated dyes.
基金All authors thank the Agence Universitaire de la Fran-cophonie(AUF)for financial support(PCSI 59113PS 014)Professor Jean-François Verchère from the University of Rouen(France)for his advice,fruitful dis-cussions,strong encouragement and exemplary coopera-tion.
文摘The technique of supported liquid membranes was used to achieve the facilitated transport of Cr(III) ions, using tow amphiphilic carriers, the methyl cholate and resorcinarene. For prepared SLMs, toluene as organic phase and film of polyvinylidene difluoride, as hydrophobic polymer support with 100 μm in thickness and 0.45 μm as the diameter of the pores. The macroscopic parameters (P and J0) on the transport of these ions were determined for different medium temperatures. For these different environments, the prepared SLMs were highly permeable and a clear evolution of these parameters was observed. The parameter J0 depended on the temperature according to the Arrhenius equation. The activation parameters, Ea, ΔH≠ and ΔS≠, for the transition state on the reaction of complex formation (ST) , were determined. To explain these results for this phenomenon, and achieve a better extraction of the substrate, a model based on the substrate complexation by the carrier and the diffusion of the formed complex (ST) was developed. The experimental results verify this model and determine the microscopic parameters (Kass and D*). These studies show that these parameters Kass and D* are specific to facilitated transport of Cr(III) ions by each of the carriers and they are changing significantly with temperature.
基金the National Natural Science Foundation of China (Grant No. 39870221).
文摘Both HA-CdS and HB-CdS (Hys-CdS, Hys represents HA, HB) complex systems were established according to the dynamics of heterogeneous electron-transfer process μ = Es/s+-ECB <0. In these systems, the electron transferring from 1Hys* to conduction band ofCdS is feasible. Determined from the fluorescence quenching, the apparent association constants (Kapp) between Hypocrellin A(HA), Hypocrellin B (HB) and CdS sol. were about 940 (mol/L)-1, 934 (mol/L)-1, respectively. Fluorescence lifetime measurements gave the rate constant for the electron transfer process from 1HA*, 1HB* into conduction band of CdS semiconductor as 5.16×109 s-1, 5.10×109 s-1, respectively. TEMPO (2,2,6,6-tetramethy-1-piperdinyloxy), a stable nitroxide radical, was used in the kinetic study of the reduction reaction taking place on the surface of a CdS colloidal semiconductor, kinetics equation of the reaction was determined with the electron paramagnetic resonance (EPR) method, and the reaction order of TEMPO is zero. When Hys were added, the rate of EPR increased greatly. By comparing rate constants, the Hys-CdS systems were revealed to be about 350 times more efficient than CdS sol. alone in the photoreduction of TEMPO under visible light. It suggests that Hys can be used as efficient sensitizers of a colloidal semiconductor in the application of solar energy.
