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The title hydrated copper(I)–L-cysteine–chloride complex has a polymeric structure of composition {[Cu16(CysH2)6Cl16]·xH2O} n [CysH2 = HO2CCH(NH3 +)CH2S− or C3H7NO2S], namely, poly[[tetra-μ3-chlorido-deca-μ2-chlorido-dichloridohexakis(μ4-L-cysteinato)hexadecacopper] polyhydrate]. The copper atoms are linked by thiolate groups to form Cu12S6 nanoclusters that take the form of a tetrakis cuboctahedron, made up of a Cu12 cubo-octahedral subunit that is augmented by six sulfur atoms that are located symmetrically atop of each of the Cu4 square units of the Cu12 cubo-octahedron. The six S atoms thus form an octahedral subunit themselves. The exterior of the Cu12S6 sphere is decorated by chloride ions and trichlorocuprate units. Three chloride ions are coordinated in an irregular fashion to trigonal Cu3 subunits of the nanocluster, and four trigonal CuCl3 units are bonded via each of their chloride ions to a copper ion on the Cu12S6 sphere. The trigonal CuCl3 units are linked via Cu2Cl2 bridges covalently connected to equivalent units in neighboring nanoclusters. Four such connections are arranged in a tetrahedral fashion, thus creating an infinite diamond-like net of Cu12S6Cl4(CuCl3)4 nanoclusters. The network thus formed results in large channels occupied by solvent molecules that are mostly too ill-defined to model. The content of the voids, believed to be water molecules, was accounted for via reverse Fourier-transform methods using the SQUEEZE algorithm [Spek (2015). Acta Cryst. C71, 9–18]. The protonated amino groups of the cysteine ligands are directed away from the sphere, forming N—H...Cl hydrogen bonds with chloride-ion acceptors of their cluster. The protonated carboxy groups point outwards and presumably form O—H...O hydrogen bonds with the unresolved water molecules of the solvent channels. Disorder is observed in one of the two crystallographically unique [Cu16(CysH2)6Cl16] segments for three of the six cysteine anions.

A series of novel isonicotinoyl hydrazones based on pyridoxine (vitamin B6) were synthesized. The synthesized compounds were evaluated for their antimycobacterial activity on M. tuberculosis H37Rv strain. The most potent compound 13 showed good activity on H37Rv strain and on clinical isolates of M. tuberculosis with multidrug-resistant tuberculosis (TB) profile included first- and second-line drugs. Cytotoxicity studies of compound 13 on human embryonic kidney cells, human liver, human mesenchymal stem cells, and human embryonic lung cells in vitro demonstrated it is 2–3 times less toxicity then isoniazid and 1.5–2 less toxicity than ethambutol and moxifloxacin. Compound 13 showed weak complexation with Fe3+ ions, low acute toxicity (LD50 > 2000 mg/kg per os on mice) and the identical to isoniazid and significantly better than ethambutol and moxifloxacin efficacious in the mouse model of drug-sensitive (H37Rv) TB. These facts make him a promising candidate for future developments of antitubercular drugs.

Syntheses under shock in nitrogen bubbled samples of the water – formamide – bicarbonate – sodium hydroxide system at pH 8.63, 9.46 and 10.44 were performed in the stainless steel preservation capsules. The maximum temperature and pressure in the capsules reached 545 K and 12.5 GPa respectively. Using the LC-MS-MS analysis, the 21 synthesis products have been identified, including amines and polyamines, carboxamide, acetamide and urea derivatives, compounds containing aniline, pyrrolidine, pyrrole, imidazole, as well as alcohol groups. It was found that the Fischer-Tropsch-type syntheses with catalysis on the surface of the stainless steel of the conservation capsule associated with the adsorbed hydrogen cyanide reactions and transamidation processes play the main role in the shock syntheses. Formation reactions of all the above-mentioned compounds have been suggested. It was proposed that hydrogen cyanide, ammonia, isocyanic acid, aminonitrile, aminoacetonitrile, as well as adsorbed species H(a), CH(a), CH2(a), CHOH(a), NH2(a) and H2CNH(a) are especially important for the formation of the products. A reduction reaction of adsorbed bicarbonate with hydrogen to formaldehyde has been first postulated. In the studied system also classical reactions take place – Wohler’s synthesis of urea and Butlerov’s synthesis of methenamine. It was suggest that material of meteorites may be an effective catalyst in the Fischer-Tropsch-type syntheses at falling of the iron-nickel meteorites in the water – formamide regions on the early Earth. It was concluded that life could have originated due to the impact of meteorites on alkaline water-formamide lakes located near volcanoes on the early Earth.

The influence of kinetic hydrate inhibitors on the process of natural gas hydrate nucleation was studied using the method of dielectric spectroscopy. The processes of gas hydrate formation and decomposition were monitored using the temperature dependence of the real component of the dielectric constant ε′(T). Analysis of the relaxation times τ and activation energy ΔE of the dielectric relaxation process revealed the inhibitor was involved in hydrogen bonding and the disruption of the local structures of water molecules.

The equilibrium constants, spectral characteristics of complexes, formation thermodynamic parameters and constants of the chemical exchange reactions in the nickel(II) – l / d / dl -histidine (HisH) – l / d / dl -methionine (MetH) systems (25 °C, 1.0 mol dm−3 KNO3) over wide ranges of pH and ligands to metal ratio were calculated from the pH-potentiometry, multi-wavelength electronic spectroscopy, calorimetry and NMR relaxation data. Based on the DFT computation the structures of some complexes have been proposed. Significant enantioselective effects are exhibited in the formation constants and in some electronic spectra and NMR relaxation parameters of a number of complexes with the meso-forms domination. For the Ni(His)2 complex the process of alkaline catalysis of proton exchange with the short-time N-H proton removal from the coordinated imidazole fragment was characterized. It was shown that in the ligand exchange reaction between Ni(His)2 and His− the Ni(His)3− complex participates as an intermediate. It was found that the Met− thiomethyl group is not bounded in the Ni(Met)+ and Ni(Met)2 complexes but coordinated in the Ni(His)(Met) form. Main factors determining stereoselectivity in the complex formation processes and ligand exchange reactions in the systems studied were identified as trans effect, solvation effect and a new type of interligand thiomethyl group–imidazole ring weak interaction.

It was shown that rotational mobility of molecules in crystals is affected by the symmetry of their surroundings. A hypothesis was proposed for the discovered correlation. Three cases are possible for the location of the molecules with respect to the crystallographic symmetry elements: I – the location in a general position; II – the location in special positions without symmetry disordering; III – the location in special positions with symmetry disordering. According to the experimental data, the rotation barrier heights at the location of the molecules in cases I and III are lower than in case II. This fact is explained by the amplitude and phase shifts of the rotational energy profiles of two parts of the molecule in case I and by increasing the number of minima on the rotation barrier profile at disordering the molecules by symmetry in case III. The way is proposed for lowering the rotational barrier of molecules in crystals.

The kinetics of oligopeptides formation in the flow systems glycine–sodium trimetaphosphate–imidazole/N-methylimidazole at thermocyclic regime has been investigated by HPLC and 31P NMR methods in the ranges of temperature from 45 to 90 °C and pH from 8.5 to 11.5. Detailed reaction mechanisms have been proposed and justified by quantum chemical calculations using DFT method at the CAM-B3LYP/TZVP level with accounting solvent effect by the C-PCM model. A new imidazole catalysis mechanism by which imidazole reacts with cyclic N,O-phosphoryl glycine giving N-imidazolyl-O-glycyl phosphate as a key intermediate was proposed and validated. It is emphasized that while in the absence of imidazoles, prebiotic activation of amino acids occurs at the N-terminus, in the presence of imidazoles it shifts to the O-terminus. This means that in the peptide elongation N-imidazolyl-O-aminoacyl phosphates play in prebiotic systems the outstanding role similar to that of aminoacyl adenylates formed at the ATP and aminoacyl-tRNA synthetases presence in biosystems. The new crucial role of imidazoles in prebiotic evolution has been noticed. The systems used and modes of their conversion can be good models for prebiotic peptide syntheses in a flow thermocyclic regime.

Complex formation thermodynamics in the copper(II) – glycylglycylglycine (GGG·H) and copper(II) – glycylglycylglycine – l/d -histidine (HisH) systems (25.0 °C, 1.0 M KNO3) was investigated by pH-potentiometric titration and spectrophotometry methods in a wide pH range (2–13). Five hetero-ligand complexes were identified, three of which were characterized for the first time including one binuclear complex. Parameters of individual absorption spectra and ESR spectra of the heteroligand copper(II) complexes with glycylglycylglycine and histidine were obtained for the first time. Complex structures were optimized by DFT computations on the CAM-B3LYP/TZVPP and PBE/TZVPP levels with accounting solvent effect by the C-PCM model. For the complex Cu(GGG·H-2)(His)2− the rapid exchange between two isomers with axial coordination of the imidazole or carboxyl group of His− was first found. It was shown that the complex Cu2(GGG·H-2)(His)(HisH-1)2− presents as two isomers where deprotonated imidazole of the HisH-12− ligand connects two copper ions. The kinetics of glycylglycylglycine substitution by l/dl -histidine was investigated by stopped-flow technique with spectrophotometric detection and three-step scheme of the investigated process was proposed. An unusual stereoselective effect in the tripeptide substitution by anionic form of histidine was revealed and interpreted on the basis of the formation of heteroligand complexes as intermediates in overall processes, that was confirmed by DFT calculations. It is emphasized that only combination of several informative methods (pH-metry, UV–Vis-spectroscopy, ESR, stopped-flow, and DFT calculations) made it possible to reliably describe simultaneously the thermodynamics of formation, the kinetics of substitution reactions, and the structure of complexes in the complex ternary system under study.

Many physical effects, such asdcconductivity and percolation, depend on the morphology of the silicate structure and its relationship to adsorbed water. These effects play an important role in numerous technological applications, in geology, oil-extracting industry, and other practical fields. In this study, all the samples: natural montmorillonite, kaolinite, and сlinoptilolite with different exchangeable cations in their structures, – were stored in ambient air humidity. The investigation was carried by using two separate techniques, namely Dielectric Spectroscopy and a fractal analysis of electron micrographs. The aims of this work were to analyze the complex relaxation behavior of the relaxation process in temperature range –70°C ÷ +70°C and to determine the fractal dimensions of silicates from the dielectric response at percolation. Dielectric measurements in the frequency range of 1 Hz ÷ 1 MHz were performed using a BDS 80 Dielectric Spectrometer based on an Alpha Impedance Analyzer (Novocontrol). The micrographs were analyzed using a special Matlab based program. The analysis of aspects of the dielectric relaxation spectra related to percolation was used for the determination of the numerical characteristics of geometric heterogeneity of natural silicates. The percolation temperatures of the studied samples were determined. The percolation phenomenon in the silicates is related to the transfer of the electric excitation within the developed network of open pores due to the migration of protons and ions along the surface of connected pores on the outer surfaces of the granules. The analysis of these processes allows one to extract the fractal dimensions associated with the migration of charge carriers within the porous medium. Fractal dimensions of the silicates calculated in two ways: from dielectric spectroscopy study and from fractal analysis of the micrographs, – are in good agreement with each other. It was demonstrated that conventional method of the spatial fractal dimension determination using fractal analysis of electron micrographs leads to overestimation in the case of spatial fractal bounded by a surface fractal. The dielectric spectroscopy method is free from such overestimation.

Crystals of four new copper(II) complexes containing Cu2(AcO)4 paddle-wheel units and 1-ethyl-3-methyl­imidazolium cations have been grown from ionic liquid–water mixtures and characterized by X-ray analysis. Two of the synthesized complexes are one-dimensional coordination polymers with anionic chains and counter-ions between them., Crystals of four new copper(II) complexes have been grown from copper(II) acetate/chloride–1-ethyl-3-methyl­imidazolium acetate/chloride–water systems and characterized by X-ray analysis. The first complex, bis­(1-ethyl-3-methyl­imidazolium) tetra-μ-acetato-bis[chloridocuprate(II)], [Emim]2[Cu2(C2H3O2)4Cl2] (1) (Emim is 1-ethyl-3-methyl­imidazolium, C6H11N2), contains [Cu2(C2H3O2)4Cl2]2− coordination anions with a paddle-wheel structure and ionic liquid cations. Two of the synthesized complexes are one-dimensional polymers, namely catena-poly[1-ethyl-3-methyl­imidazolium [[tetra-μ-acetato-dicuprate(II)]-μ-chlorido] monohydrate], {[Emim][Cu2(C2H3O2)4Cl]·H2O}n (2), and catena-poly[1-ethyl-3-methyl­imidazolium [[tetra-μ-acetato-dicuprate(II)]-μ-acetato]], {[Emim][Cu2(C2H3O2)5]}n (3). In these compounds, the Cu2(C2H3O2)4 units with a paddle-wheel structure are connected to each other through chloride (in 2) or acetate (in 3) anions to form parallel chains, between which cations of ionic liquid are situated. The last compound, bis­(1-ethyl-3-methyl­imidazolium) tetra-μ-acetato-bis[aquacopper(II)] tetra-μ-acetato-bis[acetatocuprate(II)] dihydrate, [Emim]2[Cu2(C2H3O2)4(H2O)2][Cu2(C2H3O2)6]·2H2O (4), contains two different binuclear coordination units (neutral and anionic), connected through hydrogen bonds between water mol­ecules and acetate ions.

Hydration of the copper(II) bis-complexes with glycine, serine, lysine, and aspartic acid was studied by DFT and MD simulation methods. The distances between copper(II) and water molecules in the 1st and 2nd coordination shells, the average number of water molecules and their mean residence times in the hydration shells were calculated. Good agreement was observed between the values obtained and those found by DFT and NMR relaxation methods. Influence of the functional groups of the ligands and the cis-trans isomerism of the complexes on the structural and dynamical parameters of the hydration shells was displayed and explained. Analysis of the MD trajectories reveals the competition for a copper(II) axial position between water molecules or water molecules and the functional chain groups of the ligands and confirms the suggestion on the pentacoordination of copper(II) in such complexes. MD simulations show that only one axial position of Cu(II) is basically occupied at each time step while in average the coordination number more than 5 is observed. © 2017 Wiley Periodicals, Inc.

The study of confined water dynamics in clay minerals is a very important topic in aluminosilicate-surface chemistry. Aluminosilicates are among the most technologically versatile materials in industry today. Dielectric spectroscopy is a very useful method for investigating the structure and dynamics of water adsorbed on solid matrix surfaces and water in the vicinity of ions in solutions. Use of this method for the study of clay minerals has been underutilized to date, however. The main goal of the present research was to understand the relaxation mechanisms of water molecules interacting with different hydration centers in clay minerals, with a view to eventually control this interaction. Two types of natural layered aluminosilicates (clay minerals) — montmorillonite with exchangeable K+, Co2+, and Ni2+ cations and kaolinite with exchangeable K+ and Ba2+ cations — were examined by means of dielectric spectroscopy over wide ranges of temperature (from -121°C to +300°C) and frequency (1 Hz–1 MHz). An analysis of the experimental data is provided in terms of four distributed relaxation processes. The low-temperature relaxation was observed only in montmorillonites and could be subdivided into two processes, each related to a specific hydration center. The cooperative behavior of water at the interface was observed in the intermediate temperature region, together with a proton percolation. The dielectric properties of ice-like and confined water structures in the layered clay minerals were compared with the dielectric response observed in porous glasses. The spatial fractal dimensions of the porous aluminosilicates were calculated by two separate methods — from an analysis of the fractality found in photomicrographs and from the dielectric response.

Ionic liquid (1-ethyl-3-methylimidazolium acetate, [C2C1im][AcO])-copper(ii) diacetate monohydrate-water-air (O2) systems have been investigated by (13)C NMR, EPR, spectrophotometry, HPLC, and synthetic chemistry methods at different temperatures. The C-H bond activation of [C2C1im](+) with the formation of the unusual dication 1,1'-diethyl-3,3'-dimethyl-2,2'-biimidazolium ([(C2C1im)2](2+)) at 50 °C and 1-ethyl-3-methyl-1H-imidazol-2(3H)-one (C2C1imO) at 50-85 °C was revealed. Two new complexes with the above compounds, [(C2C1im)2][Cu(AcO)4] and Cu2(AcO)4(C2C1imO)2, were isolated from the systems and characterized by X-ray structural analysis. Catalytic cycles with the participation of copper(ii) acetate and dioxygen and the production of [(C2C1im)2](2+) and C2C1imO have been proposed. The catalysis presumably includes the formation of the Cu(II)(O2)Cu(II) active centre with μ-η(2):η(2)-peroxide bridging in analogy with tyrosinase and catechol oxidase activity.

The formation of copper(II) complexes with L- and DL-histidine (HisH) has been studied by means of pH-potentiometry and spectrophotometry over a wide range of pH (2-14), ligand-to-metal ratio (1 : 1-15 : 1), and temperature (15-55 °C) in aqueous solutions with 1.0 mol dm(-3) KNO(3) as background. Formation constants and spectral characteristics of 13 complex types were found. Fine stereoselective effects have been detected with preferential coordination of two ligands with identical configuration in Cu(His)(HisH)(+) and opposite configuration in Cu(His)(2). The stereoselective effect for Cu(His)(HisH)(+) is explained by hydrogen bond formation between the carboxyl and imidazolyl groups of neighboring ligands at cis-arrangement of amino groups (3N(eq)-form). The opposite sign of stereoselective effect for Cu(His)(2) is derived from favourable axial coordination of the imidazole group in meso-form with cis-structure (3N(eq)N(ax)-form). A significant tetrahedral distortion was revealed for the first time in the prevalent cis-isomer of the Cu(L-His)(2) 4N(eq)-form. These findings were confirmed by EPR data and DFT computations at the B3LYP/TZVP level. The prevalence of cis-isomers for these complexes has been assigned to the rather strong trans effect of the amino groups. The structures of other detected complexes are briefly discussed on the basis of spectroscopic data. Chemical exchange reactions in the copper(II)-L/DL-hishidine systems have been investigated by the NMR relaxation of water protons. A unique proton exchange reaction with short-term proton dissociation from the coordinated imidazolyl group catalyzed by hydroxide ion was characterised for the first time. The discovered enantioselective effects in the ligand exchange reactions between Cu(His)(2) and HisH or His(-) species were attributed to the associative substitution mechanism.

Chemically Induced Dynamic Electron Polarization (CIDEP) spectra of transient radicals generated by laser pulse with λ = 248 nm in solutions of melamine in ethylene glycol have been studied by means of time-resolved (TR) ESR at room temperature. The main products are radicals of the solvent molecules formed through abstraction of hydrogen from ethylene glycol by excited melamine molecules and a melamine radical with attached hydrogen atom on melamine. Parameters obtained from well resolved TR ESR spectra coincide with parameters of radical of ethylene glycol HOC HCH 2 OH and methylol CH 2 OH, and an unresolved ESR spectrum was attributed to the melamine radical. The electron spin polarization results from the radical pair mechanism (RPM) involving S–T 0 mixing (ST 0 M) and additionally from a small part of triplet mechanism (TM). In order to establish the possible structure and nature of melamine radical quantum-chemical calculations by the DFT B3LYP method using several different basis sets have been done. The reaction pathway and mechanisms of alcohol and melamine radicals formation are proposed and supported by DFT calculations within B3LYP and CIS(D) methods. Melamine and ethylene glycol free radicals relaxation time T 2 was estimated as 1.5 and 0.5 μs, respectively.

Thiourea, PhNHC(S)NHP(O)(OPri)2 (LH) chelates of CoII, NiII, and PdII ions have been obtained and investigated by single-crystal X-ray diffraction, UV, IR, NMR spectroscopy, and EI mass-spectrometry. The unusual 1,3-N,S-coordination via sulfur and NP(O) nitrogen atoms has been found in the trans-square-planar NiL2 and PdL2 complexes, whereas the 1,5-O,S-coordination is realized in the tetrahedral CoL2 complex. DFT calculations have revealed significant stabilization of the 1,3-N,S-structures due to stronger crystal field and the NH–O P hydrogen bonds.

The crystal structure of the complex [Ni{PhNHC(S)NP(S)(OPri)2-S,S}2] has been determined and its behavior in dichloromethane solution investigated by NMR 31P spectroscopy. The X-ray structural analysis shows the nickel atom at the symmetry center in a distorted square-planar arrangement with trans-disposition of the ligands. The six-membered cycle NiS(1)PNCS(2) has the form of the asymmetric boat. In dichloromethane solutions of the compound four signals have been detected by 31P–{1H} NMR method. These signals are related to three diamagnetic square-planar isomers with different dispositions and conformations of two ligands in anti-orientation: trans-chair–boat (A), cis-boat–boat (B), and trans-boat–boat (C). These isomers are in slow exchange equilibria. It was shown that all these forms are in rather fast chemical exchange with minor (unobserved) paramagnetic pseudo-tetrahedral isomers (AT, BT, and CT). The thermodynamic constants of equilibria between A, B, and C as well as rate constants and activation parameters for conversion of three square-planar to respective pseudo-tetrahedral forms were calculated from the 31P–{1H} NMR data.

Copper(II) bis-complexes with N-phosphoryl thioureas, RN ′ HC ( S ) NP ( O ) ( OPr i ) 2 - {R = phenyl (I), cyclohexyl (II)}, have been obtained and investigated in liquid and frozen toluene solutions. Equilibria between trans-S,N and cis-S,N-isomers have been revealed and described by EPR method. In contrast to more usual S,O-forms, trans-S,N-isomers demonstrate large superhyperfine splitting from N and P atoms simultaneously. From EPR spectra anisotropic hyperfine, superhyperfine, and g-tensor parameters obtained and the symmetry of the metal ion surrounding analyzed. Rhombic anisotropy of copper(II) hyperfine and axial symmetry of N and P superhyperfine splitting resolved. Structural, hydrodynamic, and magnetic characteristics of the complexes established experimentally were supported by DFT calculations. According to EPR and DFT studies, tetrahedral distortion is higher in cis-S,N than in trans-S,N forms for steric reasons and slightly higher in I(S,N-trans) isomer than in II(S,N-trans) one due to the electron-donating effect of cyclohexyl substituent. The domination of S,N- over S,O-coordination is explained by the effects of the crystal field stabilization and the formation of the intramolecular hydrogen bonds.

To develop the prebiotic peptide synthesis problem the oligopeptides formation kinetics in the glycine – sodium trimetaphosphate – imidazole system in water has been investigated in flow and batch ...

The possibility to determine the relatively small organic compound conformations by the approach on the basis of the analysis of the residual dipolar couplings1H−13C in the molecules partially aligned in lyotropic liquid crystalline media has been considered. This approach has been used in the nuclear magnetic resonance investigation of the triglycine structure in lyotropic medium (cetylpyridinium bromide/n-hexanol). The conformation of triglycine in solution has been established astrans-trans on the basis of the experimental data of observed couplings.

A novel approach to the determination of the spatial structure of oligopeptides on the basis of an analysis of the residual dipolar couplings 1 H– 13 C assisted by quantum-chemical computations with considering solvent effects is proposed to characterize the conformations of the tripeptides GlyGlyHis and GlyGlyTyr with significant folding of the latter to left-handed helix.

Structural features and dynamical behaviour of the copper(ii) bis-complexes with glycine, d-alanine, d-valine, l-serine, l-aspartic acid, l-glutamic acid, l-lysine, l-proline, and sarcosine were studied by combined EPR and NMR relaxation methods. The cis and trans isomers were unambiguously assigned and characterized by EPR data. It was found that addition of a salt background has an influence on the cis-trans isomer equilibrium in favour of the formation of the cis isomer. By comparison of NMRD, DFT computations, and structural data it was shown that only one water molecule is coordinated in the axial position of these complexes. The increased exchange rates of this molecule found for Cu(l-Asp)2(2-), Cu(l-Glu)2(2-), Cu(l-LysH)2(2+), and Cu(l-Pro)2 were attributed to its pushing out by side chain groups of the ligands. By simulation of NMRD profiles an increase of lifetimes of the copper(ii) 2nd coordination sphere water molecules was revealed in the presence of additional carboxylic, alcoholic, or ammonium groups of the ligands, as well as the pyrrolidine ring of proline. The very short lifetimes of the 2nd coordination sphere water molecules (4-13 ps at 298 K) were explained in terms of the Frank-Wen structural model by the existence of cavities which draw in quickly enough water molecules from the 2nd coordination sphere.

The title complex has been studied by 1H and 31P NMR spectroscopy and found to undergo reversible dissociation of its neutral ligands and interconversion of its neutral and anionic ligands; the kinetic parameters of these processes and the crystal structure of the complex were determined; a new ligand exchange mechanism with unusual high spin–low spin transition during the ligand dissociation was suggested.

Rotational dynamics of the copper(II) bis-complexes with glycine and L-aspartic acid has been studied by EPR and NMR relaxation methods in aqueous solutions at several temperatures. Dynamical parameters obtained by EPR were compared with nuclear magnetic relaxation dispersion (NMRD) results and were found to be in a good agreement. From EPR data dominating trans isomer for Cu(Gly)2 and cis isomer for Cu(L-Asp)2 2- was found. On the basis of distance of closest approach of protons to central ion inferred from NMRD and crystal structure data the average slope angles of axial water molecule to equatorial plane were calculated and axial coordination of only one water molecule in the Cu(L-Asp)2 2- complex was established.

EPR, NMR relaxation methods, and DFT calculations were jointly used to investigate the structural and dynamical characteristics of solvation shells of copper(II) complexes with iminodiacetic acid, glycylglycine, and glycyglycylglycine in comparison with the copper(II) bis-glycinate studied previously. A strong trans influence of deprotonated peptide nitrogen was revealed in EPR spectra parameters of copper(II) complexes with oligopeptides. With models of the experimental NMRD data and literature X-ray structural information, it was suggested that only one water molecule coordinates in axial position of copper(II) complexes with glycine and di- and triglycine (Cu(Gly)2, Cu(GGH(-1)), and Cu(GGGH(-2))(-)), and the copper ion in these complexes is pentacoordinated, while in the iminodiacetate complex, Cu(IDA), both apical positions can be occupied by solute molecules. The obtained structural results were confirmed by DFT calculations of structures of studied compounds using different functionals and basis sets. It was shown that the donor ability of equatorial ligands and trans influence have an effect on the characteristics of the axial water bond. With increasing donor strength of equatorial ligands, pentacoordination of copper(II) complexes in water solutions becomes more preferable.

Formation constants and structures of copper(II) complexes with oxidized glutathione (L) have been determined by computer modelling of spectrophotometric and NMR relaxation measurements data over a wide range of pH (1–13) and metal and ligand concentrations in aqueous KNO3 (1 M) at 298 K. Among 11 found complexes, four forms were characterized for the first time. Based on a comparison of thermodynamic, relaxation, and optical and EPR spectroscopy parameters the structural conclusions were made. In particular, the CuLH2 and CuLH− complexes both contain two isomers which are similar to mono- and bis-aminoacid copper(II) complexes. In the Cu2L and Cu 3 L 2 2 - species one of the copper atoms is bound only with the carboxylate or carbonyl groups and the others are coordinated similarly to aminoacid chelates. Along with the last, in Cu 2 LH - 2 2 - two bridging OH− groups in one isomer or two chelate rings including deprotonated peptide nitrogen and glycinyl carboxylate oxygen in another are also present. In Cu 3 L 2 H - 4 6 - the mixed variant of coordination between CuL2− (CuN2O2) and Cu 2 LH - 4 4 - ( CuN 3 O ) is realized. The structures of polynuclear complexes have been optimized in density functional theory computations. Rate constants of ligand exchange reactions of Cu ( LH ) 2 4 - and CuL 2 6 - with participation of the LH3− and L4− forms were determined for the first time. Factors determining rates of these processes have been revealed and their proceeding by associative substitution mechanism shown.

A new approach providing a direct calculations of equilibrium constants, parameters of the chemical exchange reactions, and spectral characteristics of complexes on the basis of data of several methods including pH-potentiometry, multi-wavelength electronic spectroscopy, and NMR relaxation within a single computer program was proposed and realized in the program STALABS. Application of the STALABS program has been demonstrated on the example of investigation of the complex nickel(II) - L-histidine system by joint usage of the above three methods.

Two different types of natural layer aluminosilicates (clay minerals), montmorillonite with the exchangeable K+ and Ni2+ cations and kaolinite with the exchangeable K+ and Ba2+ cations, were investigated by dielectric spectroscopy. The different effects of water adsorption in montmorillonites and kaolinites on the dielectric response were observed in wide temperature (−90°C ÷ +140°C) and frequency (1 Hz ÷ 1 MHz) ranges. The influence of the nature of the hydration centers on adsorbed water dynamics and influence of ions nature on the activation energy values of the relaxation processes were discussed.

Dielectric spectroscopy was applied to natural clay mineral - montmorillonite with the exchangeable K+ and Ni2+ cations where the effect of water adsorption in the samples on the dielectric response was examined in the temperature from ?115?C to ?75?C and frequency from 1 Hz to 1 MHz ranges. Two relaxation processes (1 and 2) were revealed. The process 1 was related to the adsorbed ordered water structures formed on the interior surface of interlayer channels while the relaxation process 2 was attributed to the disordered water structures built between two surface water monolayers.

Among the new compounds of N-(thio)phosphorylthiomides. the copper(II) complex with N-diisopropoxyphosphorylthiohenzamide (Cul. 2) exhibits series of unusual properties which have been extcnsively investigated in the present work. The X-ray structure of CuL2 has been determined Crystals of CuL2 are monoclinic. P21/c, a = 15.610, b = 11.880, and c = 18.320 A, β = 106.74°. Z = 4. The CuL2 complex has the cis-structure with Cu-S distances ranging from 2.238 to 2.253 A and Cu-O distances being from 1.919 to 1.937 A (Figure).