In order to find a new crystal modification of lagochiline with a better water solubility instead of the well known insoluble monohydrate form, the information of crystalline products has been investigated under various conditions. The modification searched is shown to exist indeed in an anhydrous form. It is possible to obtain it by: 1) crystallization from solutions with no traces of water, 2) crystallization at 120^oC from solutions in butylacetate and 3) dehydration of the hydrate form. Water solubility of the form obtained is 20 mg/ml and, unfortunately, still insufficient for the practical use of lagochiline as an effective bloodstopping remedy. Crystal data of anhydrous lagochiline are: C₂₀H₃₆O₅, monoclinic, space group P2₁, a = 8.306(1), b = 17.443(2), c = 14.028(3) Å, ß = 106.85^o (1), V = 1943(1) Å ³, Z = 4, D_x = 1.22 g/cm³. The structure has been refined to the final R value of 0.049 for 1984 observed reflections.
The complicated system of the intermolecular H-bonds incorporates lagochiline molecules to the three dimensional H-bonded network. The realization of this network is possible due to the adoption, by one of two lagochiline molecules, of the conformation unusual for an isolated molecule.

Formation of 4-benzyl-2-phenyl-1,3-oxazolium-5-olate was observed during carbodiimide-mediated N-benzoyl- phenylalanyl-leucine methyl ester synthesis. This meso- ionic compound can also be obtained by tautomeric transformation of 4-benzyl-2-phenyl-5(4H)-oxazolone in yield (3% to 60%) depending on the type of solvent and tertiary amine catalyst used.

A series of triazolothiadiazines with an aryloxymethyl substituent at the 3-position and an aryl sydnone at the 6- position were synthesized. Several compounds showed antiinflammatory activity.

Effects of solvent and base on the reaction of p-cresol with formaldehyde were studied using a liquid SIMS method. In all cases, complex mixtures of p-methylcalix[n]arenes were obtained and selectivities depended on the cation type and solvent used. Two pure products, p-methylcalix[7]arene and p-methylcalix[8]arene, were isolated.

Sulfanolysis of tris(2-cyanoethyl)phosphine oxide (chalcogenide) gave new compounds of tris(2- thiocarbamoylethyl)phosphine oxide (chalcogenide) type, alkaline hydrolysis of which afforded sodium salts of tris(2-carboxyethyl)phosphine chalcogenides. Two compounds, OP(CH₂CH₂CONH₂)₃ and OP(CH₂CH₂CSNH₂)₃were studied by X-ray structure analysis. The coordination sphere around phosphorous atom is in both cases approximately tetrahedral.

A new method for the preparation of N,N'-carbonyl-bis-amino acid esters by reaction of bis(4-nitrophenyl)carbonate with amino acid esters is described. When the carbonate reacts with two equivalents of a peptide ester, N,N'-carbonyl-bis(peptide ester) is obtained but, a hydantoin derivative is formed as a side product. The hydantoin derivative is a major product, when equimolar amounts are allowed to react. Usefulness of this method for preparation of larger N,N'-carbonyl-bis-peptides is demonstrated by the synthesis of the respective product from C-terminal hexapeptide of Substance P linked to the Merrifield resin.

3,5-Dimethyl-4-(benzotriazol-1-ylmethyl)-1-phenylpyrazole (5) and 1,3,5-trimethyl-4-(benzotriazol-1- ylmethyl)pyrazoles (17) were prepared and alkylated with various alkyl bromides. Treatment of these compounds with alkyl Grignards led to a variety of 4-substituted-3,5-dimethylpyrazoles.

A detailed conformational analysis of an equipotent agonist of NK-1 and NK-2 tachykinin receptors - scyliorhinin I in DMSO-d₆ was carried out by ¹H NMR (DQF-COSY, TOCSY, NOESY and ROESY) and molecular dynamics calculation methods. Two groups of conformations (major and minor) were obtained based on the experimental data. Characteristic of the lowest energy conformer of the major species is the presence of two beta-turns: the first one, type IV at the N-terminus in the 1-4 fragment, the second one, type III', with Lys5 and Phe6 in positions i + 1 and i + 2, respectively. The other conformers of this group contain an additional type IV ß-turn with Phe6 and Tyr7 in the centre. Minor species represents a more extended structure with one type VI beta-turn present in the fragment 2-5. The common motive for all low energy conformers obtained is the presence of a bent structure in the fragment 4-8 of the peptide backbone. The results obtained were compared with the published conformations of selective NK- 1 and NK-2 tachykinin agonists.

Oxidation of aromatic aldoximes with one-electron oxidant ceric ammonium nitrate CAN in acetonitrile and propionitrile, has been investigated. Aromatic nitrile oxides, formed in situ, underwent 1,3- cycloaddition with aliphatic nitriles and 5-alkyl-3-aryl-1,2,4-oxadiazoles are produced in moderate to high yields. The mechanism of the reaction based on the transformations of intermediate aldazine di-N- oxides is discussed.

Title compound, C₁₂H₉N₅O₂^.HCl, was obtained by reaction of 2-amino-5-methylpyridine with 2-chloro-3-cyano-5-nitropyridine. The crystals belong to the monoclinic system, space group P2₁/c. Lattice parameters are: a = 6.8072(5) Å, b = 22.453(1) Å, c = 8.2083(7) Å, ß = 97.725(7)^o. The organic cation is essentially planar except of the nitro group, which forms interplanar angle of 19.0(1)^o with the adjacent ring plane. A conjugation of the double bonds is observed within the protonated imino group. The salt molecules, related by a center of symmetry, form dimers bonded via the N-H...Cl and C-H...Cl type hydrogen bonds.

Alkylation of the anions, generated from propionyl and butyryliron complexes, is highly stereoselective whereas reaction of the anions with deuterium oxide is non-stereoselective and leads to both stereoisomers of RS/SR and RR/SS configuration.

An a.c. four-probe setup was built to measure impedance spectra between 1 Hz and 100 kHz on solid electrolytes up to impedance values of 10 G ohm. A solution to minimize the source of errors by means of preamplifiers for current and voltage signals is presented. A special construction of the sample holder is necessary to give the best results in conjunction with the preamplifiers. The holder is designed for measurements on solid electrolytes in a wide temperature range. The performance of the setup and the residual error sources are determined. Measurements of the four-probe impedance spectra on yttria stabilized zirconia in the temperature range between room temperature and 750^oC are given as an example.

Application of the relaxation and impedance methods to the study of kinetics of the electrode reaction of silver electrode in pure molten silver chloride is presented. Basing on the inductive model of the double layer of metallic electrodes in their pure molten salts, the kinetic and activation parameters of the electrode reaction are determined. The exchange current density at 600^oC equals 4 A cm^-2, and is slightly temperature dependent, what indicates a possible barrierless charge transfer. This has been also confirmed by a kinetic type approach.

The analysis of the effect of the sinusoidal voltage perturbation signal on an electrode process has been studied. The necessity of resolving of the effective and generated sinusoid perturbation signal has been shown. The influence of the amplitude and frequency of the voltage perturbation signal on the value of the effective potential, the value of the modulus of current harmonic components and the magnitude of the electrode impedance has been discussed.

The impedance of thin film polyaniline electrodes was measured in the frequency range 0.1 Hz to 50 kHz at dc potentials corresponding to the reversible reduced and oxidized forms of the polymer. Electrical, statistical, and physical models of the thin film polymer electrode were analyzed. The reversibly reduced and oxidized polyaniline was studied from 273 to 298 K. The activation energies found for the hf and lf conductivity parameters are from 0.2 eV to 0.6 eV, respectively. In spite of the hysteresis, the activation energy was found to depend insignificantly on the direction of the dc potential scan between the reversible redox forms of polyaniline.

Ac impedance spectroscopy at ultramicrodisc electrodes is a potentially powerful technique for the investigation of electrochemical reactions, since it provides an excellent means of measuring and separating all the faradaic and non-faradaic processes occurring at the interface. In this paper we describe the theory and practice of the dc potential dependence of such measurements.

A new home-made experimental device has been developped to get accurate magnetoelectrochemical transfer functions (dI/dB)_V or (dV/dB)_I without an electromagnet and its limitations. First experiments were carried out with the ferri-ferrocyanide system onto platinum electrode. They confirm the experimental and theoretical results for steady-state as well as dynamic studies.

A general approach is proposed to investigate an electrochemical reaction mechanism by simultaneous electrochemical and electrogravimetric impedance measurements. Our approach shows that a.c. electrogravimetry may provide some useful information on the chemical nature of the species involved, in addition to the information obtained by using electrochemical impedance analysis alone. Application of a.c. electrogravimetry to passive iron in sulfuric acid solution showed that the major part of the charge transferred during a transient potential change, within the Fe passive potential range, contributes to iron corrosion rather than to the film growth. In the case of electropolymerization of polypyrrol in the presence of sodium dodecylsulfate, it was shown that the electropolymerization is followed by an oxidation process, which occurred in pores crossing the polymer.

Non-porous electrodes of NiO and LiCoO₂ are examined in molten carbonate half cells using electrochemical impedance spectroscopy. With this technique the charge-transfer resistance and diffusion properties of the oxygen reduction were measured as a function of gas composition and compared to theoretical predictions. For both electrodes the super oxide mechanism yields the best fit results, but the difference with the peroxycarbonate mechanism is very small. The exchange current densities of electrode processses are estimated from the R_ct and found to be approximately the same for both materials. By using potentiometry we showed that both electrode materials are not inert in molten carbonate. The stoichiometry of the samples depends on the Li content in the melt due to Li-doping of NiO and the Li-insertion reaction in LiCoO₂.

The resistivity of single crystal and polycrystalline Yttrium Iron Garnet was investigated by the Complex Impedance Method, distinguishing the resistivity of the bulk material rho _b from the resistivity of the grain boundaries rho_gb. Two different approaches are used for the determination of the model structure: (i) a theoretical, in which the structure is assumed apriori as a Voight- type model and (ii) a structural, in which the model is extracted from the experimental data. The second approach is based on the recently developed Differential Impedance Analysis. The results obtained illustrate the advantages of the new method, which can give information about the mechanism of the ferrite conductivity and may enhance the knowledge of the physical nature of the process.

A new method for analysis of the experimental data of the impedance spectroscopy is presented. The method is based on the assumption of a local operating model. Using the derivatives of the impedance with respect to frequency, the model parameters and their effective time-constants are calculated for each frequency. The analytical equations are used as a moving estimator over the entire frequency range. Important properties of the studied system can be derived.