[en] To apply the Cu⁺-assisted nucleophilic exchange based radioiodination of aromatic compounds for more lipophilic compounds the reaction is carried out in mixed solvent conditions. Due to its physicochemical properties acetonitrile is an attractive solvent. Although acetonitrile forms complexes with Cu⁺ decreasing the labeling yield. This article describes a method for the determination of the complex constant at labeling temperature based on a Lineweaver-Burk approach, relating the reaction rate constant and the concentration of precursor in presence of different amounts of acetonitrile. The method also allows to calculate the adjusted amount of copper salt in order to obtain the same high labeling yield as obtained in absence of acetonitrile. (author)

[en] This work presents a study on the correlation between luminescence property of Au(I)-SR (SR: thiolate) complexes and solvent polarity. Luminescent [Au₁₅(SR)_14–16]⁺ complexes were synthesized in the weakly polar solvent of toluene, while the non-luminescent [Au₇(SR)₆]⁺ species were obtained by the same synthesis method in the polar solvent of ethanol. The dependence of luminescence intensity on the mixed solvent with various toluene/ethanol ratios was also explored. It is proposed that the luminescence of Au(I)-SR complexes originates from the aggregation of the bilayer supramolecular structures induced by the weakly polar solvent. This aggregation strengthens the intra and intercomplex aurophilic Au(I)···Au(I) interactions and subsequently enhances the luminescence intensity of the complexes. - Highlights: • Luminescent [Au₁₅(SR)_14-16]⁺ complex is synthesized by dodecanethiol reducing HAuCl₄ in toluene. • Non-luminescent [Au₇(SR)₆]⁺ complex is yielded by the same synthesis in ethanol. • The relationship between the luminescence intensity and solvent polarity is studied. • Luminescence of Au(I)-SR complexes originates from aggregation of the bilayer supramolecular structures. • Aggregation increases as solvent polarity decreases.

[en] The enthalpies of transfer, ΔH_t^θ, of the solutes from pure solvent A to mixtures of A and a second solvent B were studied by isothermal titration calorimetry and analysed in terms of the new extended solvation theory. These data are considered in terms of the new developed solvation theory including variable (αn + βN), the net effect of the solute on the solvent-solvent bonding and is positive if there is a net breaking or weakening of solvent-solvent bonds

[en] Polynorbornenes prepared by vinyl addition pathway are known to have some desirable characteristics for wider application but they have some critical drawbacks such as brittleness, poor solubility and adhesion. In order to improve these drawbacks, extensive research for the successful homo- and copolymerization of polar functionalized norbornene with olefin has been carried out. Even though considerable advance has been achieved in the polymerization of polar functionalized monomers, successful catalytic systems for the homopolymerization of polar functionalized norbornene are rare. In this study, a novel successful catalytic system for the polymerization of polar functionalized norborene is proposed. This system employs Pd β-diketiminate/borate cocatalyst in water/organic mixed solvents and it is unique due to introduction of water as a component of solvents. Polymers obtained in this study show high Mw with narrow PDI. Effects of several reaction parameters to the polymer activity and properties are investigated and optimal catalytic system are proposed

[en] In the present work, the chemistry of the positronium (Ps) species has been investigated in pure benzene, pyridine and their mixtures with pyridine concentrations at 4.12, 6.18 and 8.24 M, respectively, using the Doppler-broadened line-shape analysis technique. It is seen that the intensities of para-(p-Ps) and ortho-Ps (o-Ps) in benzene and that of p-Ps in pyridine follow the Ore-model predictions while the intensity of o-Ps in pyridine is much lower than expected from this model. On the basis of these observations and of decrease in o-Ps lifetime with increasing pyridine concentration in various organic solvents as reported in literature, it is concluded that pick-off is not the only quenching mechanism for Ps in organic solvents and pyridine is a quencher of Ps-species rather than an inhibitor. Calculations carried out considering a diffusion-controlled mechanism of Ps-quenching in pyridine via unstable (dissociative) complex/adduct formation and the bubble model show that the quenching rate is diffusion controlled and the pick-off rate is in accordance with the free-volume model. These conclusions were confirmed in the mixtures of benzene and pyridine. (author)

[en] By using the potentiometric method the following quantities have been determined: acidity constants of molecular acid, K_a(HA), of cationic acid, K_a(BH⁺), anionic and cationic homoconjugation constants, K_AHA^- and K_BHB⁺, respectively, as well as molecular heteroconjugation constants, K_AHB, in (n-butylamine+acetic acid) systems without proton transfer in binary (acetonitrile+1,4-dioxane), AN+D, solvent mixtures. The results of these measurements have shown that the magnitudes of the molecular heteroconjugation constants do not depend on the 1,4-dioxane content in the mixed solvent, i.e., on solvent polarity. It has also been found that in the (acid+base) systems without proton transfer, the manner of carrying out the titration (direct B+HA vs. reverse HA+B) does not affect the magnitudes of the molecular heteroconjugation constants

No abstract available

[en] In the original proposal to study mixed solvent electrolyte solutions, four major goals were formulated: fundamental modeling of mixed solvent electrolytes using numerically solved integral equation approximation theories; evaluation of intermolecular pair potential models by computer simulation of selected systems for comparison with experiment and the numerical integral equation studies; development of fundamentally based correlations for the thermodynamic properties of mixed solvent electrolyte solutions using analytically solvable statistical mechanical models; and extension of experimental database on mixed solvent electrolytes by performing vapor-liquid equilibrium measurements on selected systems. This paper discusses the progress on these goals

[en] PVA was dissolved in mixed solvent (DMSO and water) and followed by several freeze-thaw cycles in a mold to produce PVA membrane. Surface modification of PVA membranes by HA molecules was investigated to improve the hydrophilicity of the membrane surface thereby reducing adsorption of the proteins onto the membrane. The surface composition, water contact angle, optical and mechanical properties, surface morphology, cell compatibility and protein adhesion were systematically investigated. ATR-FTIR spectra, XPS, SEM and AFM indicated that PVA membranes were successfully modified by grafting of the HA. The modified membranes showed increased hydrophilicity and cytocompatibility, decreased surface roughness and mechanical properties, and suppressed cell and protein adhesion compared to the pristine membrane. In general, the achievement of the HA coating with anti-adhesive property can potentially be widely used on surface modification of artificial cornea and other biomedical implants. (paper)

[en] The formation constants of thiocyanate complexes of Eu(III) and Am(III) in trace concentrations were investigated in mixed solvent (CH₃OH+H₂O) solutions of different ionic strength. Furthermore, in paper electrophoresis, the moving velocities of the species of Eu(III) and Am(III) were investigated in 1.1M (H, Na)(SCN, ClO₄) mixed solvent (CH₃OH+H₂O) solutions. The results showed that the difference between the velocities of Eu(III) and Am(III) is explained by the difference of the mean charges calculated by the formation constants of thiocyanate complexes of Eu(III) and Am(III) in the solution. (author)