P. R. Smirnov

Polymorphism of 4-tert-butylcalix[4]arene upon formation of n-hexane and acetonitrile complexes and thermal desolvation

Simultaneous analysis of X-ray powder diffraction patterns and DSC traces for 4-tert-butylcalix[4]arene-n-hexane and 4-tert-butylcalix[4]arene-acetonitrile compounds as functions of thermal history allows us to reveal the complex relationship between guest-free polymorphic products and desolvation of 4-tert-butylcalix[4]arene inclusion compounds.

Concentration dependence of the structure of aqueous solutions of lutetium nitrate according to X-ray diffraction

Aqueous solutions of lutetium nitrate over a wide range of concentrations are studied by X-ray diffraction under standard temperature and pressure. The low-angle peaks in experimental scattering intensity curves are interpreted. It is shown that the structure of these solutions can be of two types. It is found that a saturated solution and solutions concentrated to a molar ratio of 1: 20 have a quasi-crystalline structure resulting from interionic interactions. It is determined that dilute solutions form a water-like structure characterized by a tetrahedral network of hydrogen bonds between the water molecules. It is found that low-angle peaks also appear in the intensity curves of dilute solutions; this proves that the so-called “long-range” order is preserved in these solutions. It is revealed that in all the studied systems, the contributions to the total scattering pattern that are responsible for the occurrence of pre-peaks are intercationic interactions.

An X-ray diffraction study of aqueous solutions of lutetium trichloride

The X-ray diffraction analysis is used to study aqueous solutions of lutetium chloride in a wide concentration range under standard conditions. Small angle peaks on the functions of the X-ray scattering intensity and the maxima of radial distribution functions of the atomic-electron density are interpreted. It is found that highly concentrated solutions are characterized by a unique quasi-crystalline structure distinguished by short- and long-range ordering. Dilution of solutions results in that the own structure of the solvent starts to play the major role in the structure of the systems. It is established for the first time that small angle peaks on the scattering intensity functions are also manifested for diluted solutions, which indicates that long-range ordering is preserved in them.

Chemolysis of calcium oxalate stones: study in vitro and possible clinical application

The flow cell modeling clinical conditions have been used to study the interaction between dilute chemolytic solutions and large calcium oxalate renal stones. The stone treatment with 5% disodium ethylenediaminetetraacetate aqueous solutions or citrate buffer are found not to provide notable disruption of the samples studied. The significant improvement is reached with the mixed compositions containing both natural and synthetic chelating reagents:citrate and ethylenediaminetetraacetate ions as well as an antibiotic. Description of the chemolytic irrigation, numerical results and their possible clinical application are the main topic of the present research.

Concentration dependence of the structure of aqueous solutions of samarium trichloride according to X-ray diffraction

Aqueous solutions of samarium chloride in a wide range of concentration under ambient conditions are studied by X-ray diffraction analysis. The small-angle peaks in experimental scattering intensity curves are interpreted. It is shown that highly concentrated solutions are characterized by a unique structure that differs heavily from the structure of dilute systems. It is found that small-angle peaks also appear in the intensity curves of dilute solutions, indicating that the so-called long-range order is preserved in these solutions. It is revealed that the contributions to the total scattering pattern that govern the appearance of prepeaks are interionic interactions of different types (e.g., cation-cation, anion-cation, and anion-anion interactions) in concentrated systems and the distances between the cations in dilute solutions.

Effect of concentration on the structure of aqueous solutions of gadolinium chloride and gadolinium nitrate as probed by X-ray diffraction

Aqueous solutions of gadolinium chloride and gadolinium nitrate are studied by X-ray diffraction over wide ranges of concentrations under standard temperature and pressure. Small-angle peaks on measured scattering intensity curves are interpreted. Small-angle peaks are found not only on the intensity curves for concentrated solutions, but also on those for dilute systems, and this proves that these systems retain a long-range order. Diverse types of ion-ion interactions are shown to be the major contributors to the overall scattering pattern that are responsible for the appearance of pre-peaks.

Polymorphic conversions of 4-tert-butylcalix[4]arene upon the formation and thermal destruction of a complex with n-hexane

Complex polymorphic conversions of 4-tert-butylcalix[4]arene upon the formation and thermal destruction of a complex with n-hexane were revealed by combined analysis of powder X-ray pictures and data obtained by differential scanning calorimetry.

Structural parameters of the immediate environment of ions in saturated aqueous solutions of lanthanide chlorides, according to X-ray diffraction data

Saturated aqueous solutions of lanthanide chlorides are studied by means of X-ray diffraction. Models of the investigated solutions are used to calculate quantitative characteristics of the immediate environment of ions in solutions using the obtained experimental data. It is established that all of the investigated systems are characterized by similar structures. Cations coordinate six solvent molecules in the first coordination sphere as the Ln3+–OH2 distances become shorter upon transitioning from light to heavy ions. Non-contact ion associates form in all the systems.

Models of the nearest surrounding of ions in aqueous solutions of dysprosium chloride

Structural organization models are developed using radial distribution functions obtained earlier via XRD analysis for aqueous solutions of dysprosium chloride over a wide range of concentrations under standard conditions. The optimum variants are selected by calculating the theoretical functions for each model and comparing how they agree with experimental functions. Quantitative characteristics of the nearest surrounding of Dy3+ and Cl– ions, e.g., coordination numbers, interparticle distances, and varieties of ion pairs, are established. It is shown that the average number of water molecules in the first coordination sphere of a cation falls from 8.5 to 6 as the concentration grows; the structure of the system over the range of concentrations is determined by noncontact ion associates.

Structure of the solvation spheres of ions in aqueous solutions of LuCl3 according to X-ray diffraction data

A model approach based on the experimental XRD data was used for aqueous solutions of lutetium chloride in a wide range of concentrations under the standard conditions. The parameters of the nearest environment of ions were determined. The coordination number of the lutetium ion in solutions without solvent deficiency was found to be eight. The cation was also found to form the second coordination sphere. The transition to the concentrated and saturated solutions led to a decrease in the number of water molecules in the first sphere of the cation to six. Noncontact ion associates were shown to be characteristic for all systems under study.