Search

In an attempt to incorporate tin (Sn) into high-entropy alloys composed of refractory metals Hf, Nb, Ti and Zr with the addition of 3d transition metals Cu, Fe, and Ni, we synthesized a series of alloys in the system HfTiZrSnM (M = Cu, Fe, Nb, Ni). The alloys were characterized crystallographically, microstructurally, and compositionally, and their physical properties were determined, with the emphasis on superconductivity. All Sn-containing alloys are multi-phase mixtures of intermetallic compounds (in most cases four). A common feature of the alloys is a microstructure of large crystalline grains of a hexagonal (Hf, Ti, Zr)5Sn3 partially ordered phase embedded in a matrix that also contains many small inclusions. In the HfTiZrSnCu alloy, some Cu is also incorporated into the grains. Based on the electrical resistivity, specific heat, and magnetization measurements, a superconducting (SC) state was observed in the HfTiZr, HfTiZrSn, HfTiZrSnNi, and HfTiZrSnNb alloys. The HfTiZrSnFe alloy shows a partial SC transition, whereas the HfTiZrSnCu alloy is non-superconducting. All SC alloys are type II superconductors and belong to the Anderson class of “dirty” superconductors.

Lysosomal cysteine peptidase cathepsin B (catB) is an important tumor-promoting factor involved in tumor progression and metastasis representing a relevant target for the development of new antitumor agents. In the present study, we synthesized 11 ruthenium compounds bearing either the clinical agent nitroxoline that was previously identified as potent selective reversible inhibitor of catB activity or its derivatives. We demonstrated that organoruthenation is a viable strategy for obtaining highly effective and specific inhibitors of catB endo- and exopeptidase activity, as shown using enzyme kinetics and microscale thermophoresis. Furthermore, we showed that the novel metallodrugs by catB inhibition significantly impair processes of tumor progression in in vitro cell based functional assays at low noncytotoxic concentrations. Generally, by using metallodrugs we observed an improvement in catB inhibition, a reduction of extracellular matrix degradation and tumor cell invasion in comparison to free ligands, and a correlation with the reactivity of the monodentate halide leaving ligand., Eleven ruthenium compounds bearing either the clinical agent nitroxoline or its potent cathepsin B (catB) inhibiting derivatives were evaluated as antimetastatic agents. We demonstrated that organoruthenation is a viable strategy for obtaining highly effective and specific inhibitors of catB activities, as shown using enzyme kinetics and microscale thermophoresis. Furthermore, we showed that the novel metallodrugs significantly impair processes of tumor progression in in vitro cell based functional assays at low noncytotoxic concentrations.

This study was designed to better understand the microstructural and phase evolution of lead-free sodium potassium niobate based piezoceramics with a nominal composition (K0.5Na0.5)0.99Sr0.005NbO3 (KNNSr) during pressure-less spark plasma sintering followed by post-annealing in oxygen. The as-sintered samples were dark-coloured and electrically conductive as a result of partial reduction of Nb5+ to Nb4+ and formation of oxygen vacancies confirmed by X-ray photoelectron and Raman spectroscopy. The Rietveld refinement analysis showed that the as-sintered samples contained two perovskite phases with monoclinic Pm unit cell and slightly different unit-cell parameters. The microstructure with sub-micrometre-sized grains unambiguously confirmed that rapid heating and short dwell time hindered the grain growth. We found that post-annealing the samples at 950 °C in oxygen led to improvement in functional properties. The samples became white-coloured, the both perovskite unit cells decreased as a result of re-oxidation, while the microstructure remained essentially unchanged. The KNNSr sintered at nominal sintering temperature of 1300 °C for 3 min and post-annealed possessed a relative density of 88% and dielectric and piezoelectric properties similar to those of the conventionally sintered samples. Our findings contribute to the understanding of pressure-less spark plasma sintering of sodium potassium niobate-based materials and suggest that arrested grain growth and minimisation of alkali evaporation not necessarily lead to dense ceramic.

We present a study of the magnetic phase diagram and the magnetoresistance of a Gd–Tb–Dy–Ho–Lu "ideal" hexagonal high-entropy alloy (HEA), composed of the elements from the heavy half of the rare earth series only. The phase diagram contains an antiferromagnetic (AFM) state, a field-induced ferromagnetic (FM) state above the AFM-to-FM spin-flop transition and a low-temperature spin-glass state. The complex ( H , T ) phase diagram is a result of competition between the periodic potential arising from the electronic band structure that favors periodic magnetic ordering, the substitutional-disorder-induced random local potential that favors spin-glass-type spin freezing in random directions, the Zeeman interaction with the external magnetic field that favors spin alignment along the field direction and the thermal agitation that opposes any spin ordering. The magnetoresistance reflects complexity of the ( H , T ) phase diagram. Its temperature dependence can be explained by a continuous weakening and final disappearance of the periodic potential upon cooling that leads to the destruction of long-range ordered periodic magnetic structures. The magnetoresistance is large only at temperatures, where the AFM and field-induced FM structures are present and exhibits a maximum at the critical field of the AFM-to-FM transition. Within the AFM phase, the magnetoresistance is positive with a quadratic field dependence, whereas it is negative with a logarithmic-like field dependence within the field-induced FM phase. At lower temperatures, the long-range periodic spin order "melts" and the magnetoresistance diminishes until it totally vanishes within the low-temperature spin glass phase. The magnetoresistance is asymmetric with respect to the field sweep direction, reflecting nonergodicity and frustration of the spin system.

The conversion of the biomass-derived lipid, lignocellulosic and carbohydrate resources into renewable platform intermediates, chemicals and biofuels has been lately increasing in interest. The mechanistic reaction pathways, like hydro-deoxygenation, decarboxylation and hydrocracking, of the selected palmitic acid, as a model fatty acid, over Ni/ZSM-5 zeolite catalysts were studied. The ZSM-5 material with different Al/Si molar ratios was synthesized via a green template-free hydrothermal synthesis procedure, treated and subsequent functionalised with various Ni metal loadings. However, Ni/Al molar ratio was kept stoichiometric (Ni/Al = 0.5). The characteristic physicochemical properties of composite catalysts were studied by numerous characterization techniques, such as X-ray powder diffraction (XRD), scanning-, as well as high-resolution transmission electron microscopy (SEM/HRTEM), and X-ray photoelectron spectroscopy (XPS). NiO with an average particle size of 10–20 nm was found on ZSM-5 support. The relative Ni/Al atom fraction in Ni/ZSM-5 systems influenced their Lewis/Bronsted acidic sites, as well as the external exposed area of prepared heterogeneous structures. Furthermore, the mentioned morphological parameters affected predominant catalytic routes. Species’ production mechanism, as a consequence of Lewis/Bronsted centre weak/strong acidity, as well as their integral concentration, was proposed, mirroring the observed process kinetics, selectivity and turnover. It was demonstrated that the main obtained products were esters, aldehydes, alcohols, hydrocarbons and gases (CO2, CO…), produced by deoxygenation (e.g. decarbonylation), hydrogenation and cracking, less, though, through isomerisation.

Vanadium(V) compounds with 3,5-difluoropicolinic acid (HpicFF) and 3-hydroxypicolinic acid (H2hypic) and zinc(II) compounds with HpicFF, H2hypic and 4-methylhydroxypicolinic acid (HpicCH2OH) in the presence or absence of pyridine (py), 4-(dimethylamino)pyridine (DMAP), and 1,10-phenanthroline (phen) have been synthesized and characterized. The crystal structures of NH4[VO2(picFF)2]·1.6H2O (3·1.6H2O), NH4[VO2(hypic)2]·H2O (4·H2O), [Zn(picFF)2(H2O)2] (5), [Zn(picFF)2(py)2]·py (6·py), [Zn(picFF)2(DMAP)2]·H2O (7·H2O), [Zn(picFF)2(phen)]·2CHCl3 (8·2CHCl3), [Zn(Hhypic)2(MeOH)2] (10), [Zn(Hhypic)2(DMAP)(H2O)] (11) and [Zn(Hhypic)2(phen)] (12) were determined by X-ray crystallography. The spatial arrangement of the vanadium(V) complex 3 possesses carboxylate oxygen atoms in a mutual trans orientation while crystal structure 4 represents the first crystallographic evidence for the formation of an isomer with two picolinato nitrogen atoms in a mutual trans position. Two different spatial arrangements were found in the zinc(II) complexes with trans (5, 10 and 11) and cis (6, 7, 8 and 12) octahedral geometry. Insulin-mimetic activity of the selected VIVO, VVO2 and ZnII complexes was studied by in vitro inhibition of the free fatty acid (FFA) release from isolated rat adipocytes treated with epinephrine. All the studied metal complexes showed insulin-mimetic activity. Vanadium complexes 1–4 exhibit activities similar to VOSO4 with the Hhypic complexes being more active than the picFF ones. The zinc complexes also exhibited some insulin-mimetic activity, with the Hhypic complex (9) being more active than the other two, however, the insulin-mimetic activity of these complexes did not show more potent activity than ZnSO4.

We have synthesized a range of novel cyclometallated organoruthenium(II) complexes through ortho-C-H activation of the aryl group in 2-aryl-substituted quinazolines with [RuX2(p-cymene)]2. The beneficial effect of the carboxylate ligand on both the cyclometallation and further arylation reaction step was demonstrated. Mechanistic studies reveal that bromide and iodide anions decelerates the arylation process via in situ ligand exchange reaction. Additionally, a detailed NMR investigation explains some elementary steps in the arylation of 2-(aryl)quinazoline-halido-ruthenacycles.

Vanadium(V) compounds with 5-cyanopicolinato acid (HpicCN), pyrazine-2-carboxylic acid (Hprz) and 3-aminopyrazine-2-carboxylic acid (HprzNH2) and zinc compounds with HpicCN in the presence of 4-aminopyridine (4apy), pyridine (py) and 1,10-phenanthroline (phen) have been synthesized and characterized. The crystal structures of NH4[VO2(picCN)2] (3), NH4[VO2(prz)2] (4), NH4[VO2(przNH2)2]·H2O (5·H2O), [Zn(picCN)2(H2O)2] (6), [Zn(picCN)2(4apy)2]·C7H8 (7·C7H8), [Zn(picCN)2(4apy)] (8), [Zn(picCN)2(py)2] (9) and [Zn(picCN)2(phen)]·C7H8·2MeOH (10·C7H8·2MeOH) were determined by X-ray crystallography. The spatial arrangements of all the vanadium(V) complexes are similar, having carboxylate oxygen atoms in a mutual trans orientation. In the zinc bis(5-cyanopicolinato) complexes three different arrangements were found with trans (6) and a cis (7, 9 and 10) octahedral and square-pyramidal (8) geometries. The insulino-mimetic activity of selected VO(IV), VO2(V) and Zn(II) complexes was studied by in vitro inhibition of the free fatty acid (FFA) release from isolated rat adipocytes treated with epinephrine. All metal complexes showed insulino-mimetic activity and among them the VO(IV)–prz complex 2 was found to have higher insulino-mimetic activity than the positive control. The other vanadium compounds have activities similar to VOSO4. The Zn complexes also exhibited some insulino-mimetic activity. Introduction of the N-donor 4apy to the zinc picCN complex 8 significantly increased inhibition of FFA release compared to 6.

Physicochemical evaluation of polyethylene oxide (PEO) polymers with various molecular weights was performed at molecular (polymeric dispersion) and bulk level (powders, polymeric films, and tablets) with the aim of specifying polymer critical material attributes with the main contribution to drug release from prolonged-release tablets (PRTs). For this purpose, grades of PEO with low, medium, and high viscosity were used for formulating PRTs with a good soluble drug substance (dose solubility volume 15 ml). The results revealed a good correlation (r2=0.88) between in vivo data (pharmacokinetic parameters: Cmax and AUC) and the elastic property of PEO films determined with the nanoindentation method, demonstrating that film level can also be used for the in vivo prediction of drug dissolution. The study confirmed that polymer molecular weight and its viscosity are the most important critical material attributes affecting drug dissolution (in vitro) and in vivo bioavailability (e.g. Cmax and AUC). Our research revealed that the nanoindentation technique can distinguish well between various types of polymers, classifying PEO as the most ductile and polyvinyl alcohol as the most brittle. Finally, our study provides an approach for the determination of exact physical attributes of PEO as a critical material attribute from clinically relevant data, and it therefore fulfills the basic principles of product development by Quality by Design.

Dinuclear ferrocene-based conjugates comprising a small homochiral sequence of two aminoacids (FcCO-Pro-Ala-NHFc) were prepared using stepwise solution-phase coupling techniques. The propensity of these bioorganometallics to form tight turns that resemble those in natural peptides was investigated by means of spectroscopy and the crystal structure was determined by X-ray diffraction analysis. The experimental data were corroborated by DFT calculations. The intramolecular NHFc⋯OCFc hydrogen bond keeps the molecule in the β-turn conformation. Molecules are further organized into bilayers with the inner region containing amino acid parts with relatively strong NHAla⋯OCAla hydrogen bonds, and the outer region linked by relatively weaker ferrocene⋯ferrocene interactions. The current research again confirms the robustness of the β-turn and its persistence in solution and in the solid state of small dinuclear ferrocene peptidomimetics.

Detailed characterization of calcium aluminate rich secondary steel slag derived from two different refining processes of stainless steel production has been performed in order to gain generic knowledge about this by-product, and its behaviour as a supplementary cementitious material. Additionally, slag blended cement composites were investigated and compared to a limestone filler blended cement composites and to a reference cement composites. The results showed that the investigated slag contained several hydraulic phases, mainly in the form of calcium aluminates. In the case of the slag cement composites, a larger proportion of hydration products was observed than in the case of the limestone cement composites, as well as a higher rate of strength increase.

Seven different dioxido(pyridine-2,6-dicarboxylato)vanadate(V) compounds with pyridinium (Hpy+) (1·2H2O and 1), 2-hydroxypyridinium (H2pyon+) (2·H2O), 4-aminopyridinium (H4apy+) (3·H2O and 3), 4-(dimethylamino)pyridinium (Hdmap+) (4·H2O) and imidazolium (Himd+) (5) cations have been prepared via different pathways starting either from pyridine-2,6-dicarboxylic acid or its esters, and were structurally characterized by single-crystal X-ray diffraction. The vanadium metal center in dioxido(pyridine-2,6-dicarboxylato)vanadate(V) anion is pentacoordinated in all of the compounds: having two oxido oxygen atoms in a mutual cis position and a tridentate pyridine-2,6-dicarboxylic ligand. Study of hydrogen bonds and weak interactions in the compounds revealed the relationship between the type of cation and the hydrogen bonding network in the compounds. While in 1·2H2O, 2·H2O and 4·H2O a one-dimensional (band, pillar or chain) hydrogen bonding network via N/O–H⋯O bonds is preferred, anhydrous 3 and 3·H2O favor a two-dimensional hydrogen-bonded framework, and the Himd+ cation facilitates a three-dimensional hydrogen bonding in 5. The unique vanadium coordination environment with two easily accessible oxido oxygen atoms of the VO2+ unit is suitable for the construction of non-covalent metal–organic hybrids. In 2·H2O, 3·H2O, 4·H2O and 5 both oxido oxygen atoms of the VO2+ unit participate as acceptors, however, in 1·2H2O and 3 only one oxido oxygen atom is involved in classical hydrogen bonding. Besides N/O–H⋯O hydrogen bonding, also other weak non-covalent interactions, such as C–H⋯O, π⋯π and C–H⋯π interactions, play an important role in stabilizing the crystal lattices.

Four novel ruthenium organometallic complexes: [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-bromophenyl)-1,3-butanedione)Cl] (1), [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-bromophenyl)-1,3-butanedione)pta]PF$_6$ (2), [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-iodophenyl)-1,3-butanedione)Cl] (3) and [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-iodophenyl)-1,3-butanedione)pta]PF$_6$ (4) were synthesized and characterized by elemental analysis, infrared (IR), UV-Vis, NMR and mass spectroscopy and single-crystal X-ray diffraction. The crystal structures and spectroscopic data were compared to the previously published complexes [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-chloro-phenyl)-1,3-butanedione)Cl] (5) and [(η$^6$-p-cymene)Ru(4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butanedione)pta]PF$_6$ (6). The pairs of complexes 1 and 3 as well as 2 and 4 are isostructural, with the former crystallizing in triclinic P-1 and the latter in monoclinic P2$_1$/c. The ruthenium(II) ion is found in a pseudo-octahedral “piano-stool” geometry in all compounds. Bond lengths and angles are consistent with other complexes of this type. Complexes 2 and 4 exhibit some moderate dynamic disorder. The lack of hydrogen bonding and major π-π interactions means that most of intramolecular interactions are fairly weak and involve halogen atoms present. This was further confirmed by $^1$H-NMR spectra, where a significant difference is observed only on the ligand near the halogen atom, following an expected trend. The combined data show that the difference in any activity depends substantially on the type of the ligand′s substituted halogen atom.

The presented study describes the deterioration of a traditional pigment, malachite—[Cu2(CO3)(OH)2] in different binders, as a consequence of environmental effects acting on paint layers which were prepared according to traditional Baroque recipes. Malachite has often been reported to be very permanent in all binding media; however, investigations of aged and non-aged paint layers by means of Raman microscopy have shown instability of the carbonate part of the molecule, especially when malachite is present in an egg yolk medium. Decomposition of the pigment and the formation of degradation products such as copper oxide (tenorite—CuO) were observed. The possible formation of another copper oxide, paramelaconite—Cu4O3 was also taken into consideration. In order to obtain additional information on the degradation processes which affect malachite paint layers, supporting analytical methods, such as scanning electron microscopy and X-ray diffraction, were used. Copyright © 2014 John Wiley & Sons, Ltd.

Oxidovanadium(IV) bispicolinato compounds with dimethyl sulfoxide (DMSO), pyridine, 4-aminopyridine, 4-(dimethylamino)pyridine, and imidazole were prepared and their crystal structures determined. The coordination of VO(IV) is octahedral with the neutral ligand in cis position to the V=O moiety. X-ray crystallographic studies revealed different arrangements of the ligands around the vanadium metal center. The DMSO adduct presents the first crystallographic evidence of VO(IV) picolinato complexes with a nitrogen atom occupying the axial position trans to the V=O, leading to a geometry with both oxygen atoms from the picolinato ligands in cis position to the V=O and trans to each other. On the other hand, the compounds with N-ligands have an arrangement similar to some known structures with one carboxylic group in trans position to the V=O moiety. Quantum-mechanical calculations were performed on six possible isomers of DMSO and pyridine adducts, and their energy differences were studied.

The synthesis and conformational analysis of a series of the monosubstituted aminoferrocene-based peptides bearing homo- and heterochiral Pro-Ala sequences are described. A change of the Pro amino acid chirality can affect the secondary structure. A homochiral derivatives of t-BuCO-AA2-AA1-NHFc favour β-turns, and a disruption of the secondary structure is observed in their heterochiral analogues in solution. A detailed computational study suggested formation of γ-turns in their heterochiral derivatives. The X-ray determined crystal structures of heterochiral compounds show preference for β-turns. The calculated interaction energies pointed out the significance of the intermolecular hydrogen bonds favourable enough to overcome rearangement of a single molecule from the most stable conformer to the one adopted in the solid state. The current research pointed out the potential of the investigated compounds for the fine tuning of their conformational properties by variation of the chirality of constituted amino acids.

A simple three step synthesis of aminosubstituted 1,2,7,8-tetrahydro-2,7-naphthyridine-4- carboxylates is described. Ethyl (3-cyano-6-ethoxy-2-oxo-1,2-dihydropyridin-4-yl)acetate 3, formed by the condensation of diethyl acetone-1,3-dicarboxylate with malononitrile, was transformed with N,N-dimethylformamide dimethylacetal (DMFDMA) into (E)-ethyl 2-(3- cyano-6-ethoxy-2-oxo-1,2-dihydropyridin-4-yl)-3-(dimethylamino)propenoate 4. In further reaction the dimethylamino group was substituted with amino, hydroxy or substituted hydrazino group, followed by cyclisation to afford substituted 1-amino-7,8-dihydro-2,7-naphthyridine-4- carboxylate 6b, 1-imino-7,8-dihydro-1H-pyrano(3,4-c)pyridine-4-carboxylate 8, and 1-imino-2- aminosubstituted 1,2,7,8-tetrahydro-2,7-naphthyridine-4-carboxylates 13a-i.

It has been an established fact that finely ground calcium carbonate represents to a certain extent an active component during the hydration of Portland cement and the formation of calcium monocarboaluminate has been confirmed many times. Additionally, the formation of calcium hemicarboaluminate, as another possible compound, has been mentioned. There is, however, lack of specific information regarding these two compounds: there has been no experimental data on their hydration time-dependent formation, their interrelations, and their amount in a hardened cement paste. This paper describes the time-related formation of hemicarboaluminate and monocarboaluminate and reports for the first time in the literature the conversion of hemicarboaluminate into monocarboaluminate on the basis of X-ray diffraction by following the content of the latter using the Rietveld method. Hemicarboaluminate appears at early hydration times in calcite-containing Portland cement, even in the presence of large amounts of calcium carbonate. As the hydration progresses, a gradual conversion of hemicarboaluminate into monocarboaluminate occurs. The only detectable AFm-type compound present in well-hydrated cement is calcium monocarboaluminate.

By the condensation of malononitrile (1) with dialkyl acetone-1,3-dicarboxylates 2a, b alkyl (3- cyano-6-alkoxy-2-oxo-1,2-dihydropyridin-4-yl)acetates 6a, b are formed in contrast to an earlier report according to which diethyl 3-(dicyanomethylene)glutarate 3b was obtained in the reaction of 1 and 2a. Compounds 6a, b were transformed with DMFDMA into the corresponding (E)-alkyl 2-(3- cyano-6-alkoxy-2-oxo-1,2-dihydropyridin-4-yl)-3-(dimethylamino)propenoates 7a, b. The structures of 6a and 7a were confirmed by X-ray structural analysis.

Microwave-assisted [2+2] cycloaddition of (E)-3-dimethylamino-1-heteroaryl-prop-2-en-1-ones to dimethyl acetylenedicarboxylates gives (2E,3E)-dimethyl-2-[(dimethylamino)methylene]-3-(substituted)succinates in 8–91% yield. In the case of a 4,5-dihydrothiazoline derivative, cycloaddition also took place at the endocyclic CN double bond.

In the system BaF2/BF3/PF5/anhydrous hydrogen fluoride (aHF) a compound Ba(BF4)(PF6) was isolated and characterized by Raman spectroscopy and X-ray diffraction on the single crystal. Ba(BF4)(PF6) crystallizes in a hexagonal P 6 ¯ 2 m space group with a=10.2251(4) A, c=6.1535(4) A, V=557.17(5) A3 at 200 K, and Z=3. Both crystallographically independent Ba atoms possess coordination polyhedra in the shape of tri-capped trigonal prisms, which include F atoms from BF4− and PF6− anions. In the analogous system with AsF5 instead of PF5 the compound Ba(BF4)(AsF6) was isolated and characterized. It crystallizes in an orthorhombic Pnma space group with a=10.415(2) A, b=6.325(3) A, c=11.8297(17) A, V=779.3(4) A3 at 200 K, and Z=4. The coordination around Ba atom is in the shape of slightly distorted tri-capped trigonal prism which includes five F atoms from AsF6− and four F atoms from BF4− anions. When the system BaF2/BF3/AsF5/aHF is made basic with an extra addition of BaF2, the compound Ba2(BF4)2(AsF6)(H3F4) was obtained. It crystallizes in a hexagonal P63/mmc space group with a=6.8709(9) A, c=17.327(8) A, V=708.4(4) A3 at 200 K, and Z=2. The barium environment in the shape of tetra-capped distorted trigonal prism involves 10 F atoms from four BF4−, three AsF6− and three H3F4− anions. All F atoms, except the central atom in H3F4 moiety, act as μ2-bridges yielding a complex 3-D structural network.

Successful Rietveld refinements of seven compounds with the formulae La2Ti(1−x)Ga x O(5−x/2), where x = 0.00, 0.20, 0.50, 0.70, 0.90, 0.95 and 1.00, were performed in order to describe the solid solubility between orthorhombic (Pnam) La2TiO5 and monoclinic (P21/c) La4Ga2O9. The relationship between the end-member structures, which are already known, is discussed; the space-group change is a consequence of ordering the oxygen vacancies that become more numerous as Ga is substituted for Ti. The structures of the solid solutions are also described. The lengths of cell edges obey Vegard's rule.

A seven-step synthesis of 1-substituted 5-(2-acylaminoethyl)-1H-pyrazole-4-carboxamides 20 as the pyrazole analogues of histamine was developed. The synthesis starts with a three-step preparation of N(1)-substituted methyl 5-(2-tert-butoxycarbonylaminoethyl)-1H-pyrazole-4-carboxylates 7 from commercially available Boc-β-alanine (1). Subsequent four-step transformation of the key-intermediates 7 into the final products 20 was performed following two complementary reaction sequences comprising acidolytic removal of the Boc group, hydrolysis of the COOMe group, amidations of the COOH group, and acylations of the NH2 group. The structures of pyrazole derivatives were determined by spectroscopic methods and by X-ray diffraction.

The KxBa1−xGa2−xGe2+xO8 (x=0.6−1.0) solid solutions undergo a structural phase transition that has a significant effect on their sintering behavior and their microwave dielectric properties. The crystal structures of both phases within the solid-solution region were determined by the Rietveld method using powder X-ray diffraction data. We found that the low-temperature-stable phase is isostructural with the pseudo-orthorhombic KGaGe3O8 (space group P21/a), while the high-temperature-stable phase has a typical monoclinic feldspar structure (space group C2/m). Due to the topological differences between the two structures, the T–O bonds within the tetrahedra must be partially recombined to make a new framework, which causes an endothermic effect during the P21/a to C2/m phase transition. The correlation between the crystal structures, the microwave dielectric properties and the phase-transition behaviors were discussed in terms of the crystallographic features, the lattice parameters, and the strain-induced anisotropic peak-broadening.

Pure-silica ZSM-12, containing tetraethylammonium cations (TEA) was synthesized using a ‘two-silica’ source strategy and its structure was determined from laboratory X-ray powder diffraction data. This is the first known zeolite structure in which the positions of the TEA cations have been established. The ordered arrangement of TEA cations in the straight nonintersecting channels of the host material, which is reflected in several weak superstructural diffraction peaks, was determined by using the combination of simulated annealing and Rietveld refinement. In accordance with Raman spectroscopy, the calculations confirmed the presence of a tt . tt form of the TEA cations and the absence of the other stable form ( tg . tg ) which was also consistent with the dimensions and elliptical cross-section of the channels. Therefore in ZSM-12 structure pore (channels) geometry is directly connected with the conformation of TEA cations. The compound with a moiety formula C 16 H 40 N 2 O 84 Si 42 ( M r = 2784.28, Z = 4) crystallizes in the monoclinic Cc space group with unit cell parameters a = 25.2177(9), b = 15.1903(5), c = 24.4754(7) A, β = 108.516(2)°. The final structure, which resulted in a good agreement between calculated and observed powder diffraction pattern ( R wp = 10.17%), was additionally confirmed by results from thermogravimetric measurements and FTIR spectroscopy.

We demonstrate, for the first time, a considerable electrochemical activity of two members of lithium transition element titanates: Li 2 FeTiO 4 and Li 2 MnTiO 4 . Both materials consist of 10-20 nm particles embedded in a conductive carbon coating. We show that not the coating but the small particle size is decisive for materials' activity. Li 2 FeTiO 4 shows a stable reversible capacity of up to 123 mA hg ―1 at C/20 and 60°C which is 83% of the theoretical value for exchange of 1 electron (148 mA hg ―1 ). Li 2 MnTiO 4 could only be prepared in a nanosized form that contained about 30% of impurities. The capacity of the whole material (including impurities) is comparable to that of Li 2 FeTiO 4 but the cycling stability is much poorer. In contrast to the Fe and Mn analogues, the third member of the titanate family, Li 2 NiTiO 4 , shows a good electrochemistry even when the particle size is much larger (about 100 nm). During initial cycles at C/10 and 60°C, exchange of more than 1 electron per compound formula has been observed. The cycling stability at high temperatures, however, is poor.

Methyl ( Z)-2-(benzoylamino)-3-(dimethylamino)propenoate( 1) reacted with trimethylenemethane ( 2) to produce methyl ( Z)-2-[benzoyl(2-methylallyl)amino]-3-(dimethylamino)propeno-ate( 3), which was then converted into pyrazolederivatives 11A- H bya consecutive exchange of the dimethylamino group with hydrazinederivates 9A- H andcyclization to the ester group. Reactions of pyrazoles 11A- G withdimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate ( 6)resulted in the diastereoselective formation of 1-aryl-6′-benzoyl-4a′-methyl-5-oxo-1,4′,4a′,5,5′,6′-hexahydrospiro[pyrazole-4,7′-pyrrolo[3,4- C]pyridazine]-3′,7a′(1′ H)-dicarboxylates 12A- G. This represents a simple new pathwayto novel heterocyclic systems. On the other hand, when (dimethylamino)propenoate 3 reacted with aniline hydrochloride ( 4), followed by the cycloaddition of 1,2,4,5-tetrazine 6, dimethyl ( E)-and ( Z)-4-({benzoyl[1-(methoxycarbonyl)-2-(phenylamino)vinyl]amino}methyl)-4-methyl-1,4-dihydropyridazine-3,6-dicarboxylates( 7) and ( 8) wereformed, respectively.

The purpose of this research was to determine the influence of temperature, pH, and the addition of sodium oxide silicium oxide (soso) on the dyeability of cotton warp during the process of dip-dyeing. A simulation of the dip-dyeing technique was used. The results show a negligible influence of dip-dyeing bath temperature on the color yield of cotton warp. Lower pH values of dip-dyeing baths cause better dyeability. Addition of soso has a particular influence on the color yield of cotton warp. As a result, the dip-dyeing procedure is shortened when soso is used. The change of color of dip-dyed cotton warp, depending on different pH of the baths and on the addition of soso, was studied using x-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. XRD showed that the dyeing conditions do not affect the crystallographic form of indigo, which is form B in all cases. On the other hand, SEM revealed the reasons for the observed effects in the differences in the morphology of the indigo crystallites.

Microwave-assisted [2+2] cycloaddition reactions of 2-amino-3-dimethylaminopropenoates with acetylenecarboxylates furnished highly functionalised 1-amino-4-(dimethylamino)buta-1,3-dienes in 40–94% yields. All reactions were observed to consistently produce single geometrical isomers, and in cases where non-symmetrical acetylenes were employed the reactions proceeded in a regiospecific manner.

Dimethyl 3-oxopentane-1,5-dioate (dimethyl acetone-1,3-dicarboxylate) (1) was transformed first with (hetero)arenediazonium salts 3a - j into dimethyl 2-[(hetero)arylhydrazono]pentane-1,5-dioates 4a - j followed by reaction with N,N-dimethylformamide dimethylacetal (DMFDMA) to afford, without isolation of intermediates 5a - j, dimethyl 1-(hetero)aryl-4-oxo-1,4-dihydropyridazine-3,5- dicarboxylates 6a - j. An alternative method represents transformation of 1 with DMFDMA into dimethyl 2-[(dimethylamino)methylidene]-3-oxopentane-1,5-dioate (7) followed by treatment with (hetero)arenediazonium salts 3a - c, j to give pyridazine derivatives 6a - c,j.

A series of racemic and enantiopure (S,Z)-3-[(1H-indol-3-yl)methylidene]hexahydropyrrolo[1,2-a]pyrazin-4(1H)-one (cyclic Pro–ΔTrp) dipeptide analogues were prepared. Racemic analogues 6a–c were prepared by direct coupling of racemic cyclodipeptide enaminone (R,S)-5 with various indole derivatives. On the other hand, enantiopure analogues were prepared through a copper(I) catalyzed vinyl amidation reaction in which acyclic (S)-Pro–ΔTrp dipeptide analogues 20 and 21 were formed. Acyclic dipeptides were cyclized to enantiopure (S)-Pro–ΔTrp dipeptide analogues 24 and 25. For coupling reactions, vinyl bromides were prepared in several steps. From ethyl acetate (7), enaminone 8 was prepared and coupled with 2-methylindole and 2-phenylindole to give 9 and 10. Direct bromination of 3-(indole-3-yl)propenoates 9 and 10 at position 2 results in vinyl bromides 11 and 12. The Boc protecting group on the indole nitrogen 1′ in vinyl bromides 11 and 12 was introduced, before the copper(I) catalyzed coupling with N-Boc prolinamide 18 was performed. Enantiomeric purity of chiral intermediates and final products was determined mostly by HPLC or 1H NMR spectroscopy and X-ray diffraction.

Two new C 2 -symmetric benzoimidazolium tetrafluoroborates 19 and 20 were prepared from (1 S )-(+)-camphorquinone 1 in seven and eight steps, respectively. Thus, N 1 -((1 S ,2 R ,3 S ,4 R )-1,7,7-trimethyl-4′-methylenedihydro-3′ H -spiro[bicyclo[2.2.1]heptane-2,2′-furan]-3-yl)benzene-1,2-diamine 11 , available in three steps from 1 , was first condensed with 1 to afford amino imines 12 and 13 / 13′ . [3 + 2] Cycloaddition of trimethylenemethane (TMM) to 12 or 13 / 13′ gave cycloadduct 17 , which was successfully reduced to diamine 4 using NaCNBH 3 . Catalytic hydrogenation of methylene groups of 4 gave the methyl analogue 18 . Finally, cyclization of diamines 4 and 18 with triethyl orthoformate furnished the desired C 2 -symmetric benzoimidazolium tetrafluoroborates 19 and 20 , respectively. The structures were determined by NMR techniques, NOESY spectroscopy, and X-ray diffraction.

1,3-Dipolar cycloadditions of azomethine imines 3a and 3b, available by acid-catalyzed treatment of 3-pyrazolidinone 1 with acetone (2a) and butyraldehyde (2b), respectively, were studied. Reactions of 3a with DMAD (4) afforded a mixture of products 9 and 10a, whilst treatment of 3b with DMAD (4) gave a mixture of compound 9 and epimeric cycloadducts 10/10′b. On the other hand, cycloadducts 13a,b-16a,b were isolated as single diastereomers in 9–37% yields upon reactions of 3a,b with olefinic dipolarophiles 5–8. The structures of cycloadducts 9, 10a, 10/10′b, and 13a,b-16a,b were determined by 1H nmr and NOESY spectroscopy. The structure of compound 13a was confirmed by X-ray diffraction.

Stereoselective inverse-demand [4+2] cycloadditions of 3,6-bis(pyridin-2-yl)-1,2,4,5-tetrazine and dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate to 4′-methylenedihydro-3′ H -spiro[bicyclo[2.2.1]heptane-2,2′-furans] and 4′-methylene-1′-(4-nitrophenyl)spiro[bicyclo[2.2.1]heptane-3,2′-pyrrolidine] were studied. Cycloadditions took place stereoselectively at the exocyclic C C double bonds to give novel 11:14-isopropylidene-14-methyl-2,3-diaza-8-oxadispiro[5.1.5.2]pentadecane and 11:14-isopropylidene-11-methyl-2,3,8-triazadispiro[5.1.5.2]pentadecane derivatives in 50–98% de. The structures of the novel dispiro compounds were determined by NMR techniques, NOESY spectroscopy and X-ray diffraction.

A simple four-step synthesis of 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8 (or their 1H-pyrazol-3(2H)-one tautomers 8′) as the pyrazole analogues of histamine was developed. First, enamino lactam 3 was prepared as the key intermediate in two steps from 2-pyrrolidinone (1). Next, acid-catalysed ‘ring switching’ transformations of 3 with monosubstituted hydrazines 4 gave N-[(1-substituted 5-hydroxy-1H-pyrazol-4-yl)ethyl]benzamides 7a–k and N-[2-(2-heteroaryl-3-oxo-2,3-dihydro-1H-pyrazol-4-yl)ethyl]benzamides 7′l–o. Benzamides 7a–k and 7′l–o were finally hydrolysed by heating in 6 M hydrochloric acid to furnish 1-substituted 4-(2-aminoethyl)-5-hydroxy-1H-pyrazoles 8a–k and 4-(2-aminoethyl)-2-heteroaryl-1H-pyrazol-3(2H)-ones 8′l–o in good overall yields.

A simple and efficient synthesis of four new substituted pyrimidines, compounds 9a–d, from the title compound 3 is described. Conversion of 3 to methyl (E)-3-(dimethylamino)-2-(6-methoxy-2-phenylpyrimidin-4-yl)prop-2-enoate (4), followed by condensation with various dinucleophiles according to the ‘enaminone methodology’, afforded the target compounds 9 in medium-to-good yields.

Stereoselective [3+2] cycloadditions of trimethylenemethane (TMM) to the exocyclic C O and C N double bonds of (1S,3EZ,4R)-3-arylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones gave the corresponding spiro[bicyclo[2.2.1]heptane-2,2′-furan] and spiro[bicyclo[2.2.1]heptane-3,2′-pyrrolidine] derivatives. Further stereoselective reductions of the C N or C O bond in these cycloadducts furnished new chiral amines, diamines, and a new aminoalcohol. All cycloadditions and reductions of the C N double bonds took place from the less hindered endo-face of the (1S,3EZ,4R)-3-arylimino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones, exclusively, thus giving the corresponding products in 100% de. The structures were determined by NMR, NOESY spectroscopy, and by X-ray diffraction.

Treatment of (1Z,4R∗,5R∗)-1-arylmethylidene-4-benzamido-5-phenylpyrazolidin-3-one 1-azomethine imines 4a–d with potassium cyanide in the presence of acetic acid resulted in addition of HCN to the exocyclic C N double bond followed by β-eliminative N–N single bond cleavage (ring opening) to give the N-[(1R∗,2R∗)-3-amino-2-benzamido-3-oxo-1-phenylpropyl]benzimidoyl cyanides 6a–d in 28–85% yields. Reaction of dipole 4e with HCN furnished stable intermediate, (1′S∗,4R∗,5R∗)-4-benzamido-1-[cyano(mesityl)methyl]-5-phenylpyrazolidin-3-one (5e), in 76% yield. The structure of compound 6c was determined by X-ray diffraction.

Li2MnSiO4 has been identified recently as one of the first cathode battery materials that, at least in principle, could exchange more than 1 lithium per redox-active transition metal ion. In this article, we analyze experimentally and by computer simulations based on density functional theory (DFT) why actual experiments have not confirmed these expectations. We show that Li2MnSiO4 is unstable upon delithiation, with a strong tendency to amorphize. Detailed DFT calculations further indicate that it might be possible to obtain a stable material with a reversible exchange of more than one Li per formula unit (FU) by using an appropriate Mn/Fe mixture (solid solution) with a general formula Li2MnxFe1-xSiO4.

Combinatorial solution-phase cycloadditions of (1Z,4R*,5R*)-4-benzoylamino-5-phenylpyrazolidin-3-on-1-azomethine imines 3 to beta-keto esters 4 afforded a library of 26 bicyclic pyrazolidinones 5 in 6-89% yields and in 14-100% de. All products were isolated in90% purity according to 1H NMR, and 25 of them were analytically pure. The structures of cycloadducts were confirmed by NMR and X-ray diffraction. Most of the products were isolated as mixtures of the major (1S*,2S*,3R*,5R*,6R*)-epimers 5 and the minor (1R*,2S*,3R*,5R*,6R*)-epimers 6. Epimerization of cycloadducts 5/6 at the anomeric position 1 in solution was confirmed by 1H NMR.

In CDCl 3 solution, enantiopure ( S )-1-benzyl-6-methylpiperazine-2,5-dione ( S )- 1a formed diastereomeric C O ⋯ H –N hydrogen-bonded associates with racemic ( RS , Z )-1-benzyl-3-[(dimethylamino)methylidene]piperazine-2,5-diones 2a and 2b , ( RS )- tert -butyl pyroglutamate ( RS )- 2c and ( RS )- N -benzoylalanine methyl ester ( RS )- 2d . This resulted in splitting (doubling) of the characteristic signals in the 1 H NMR and 13 C spectra of racemic compounds 2a – d in the presence of 1 equiv of ( S )- 1a . The formation of hydrogen-bonded dimers in CDCl 3 solution was studied by 1 H NMR, 13 C NMR and 2D NMR and confirmed by the intermolecular NOE observed between the hydrogen-bonded amide protons from each of the monomeric units, ( S )- 1a and 2a – c . On the other hand, a slightly different binding mode was proposed for association of ( S )- 1a with alaninamide ( RS )- 2d . Enantiomer compositions of known (weighed) mixtures of both enantiomers of tert -butyl pyroglutamate 2c were re-determined by 1 H NMR in the presence of ( S )- 1a in CDCl 3 . The experimental values were in good agreement with the theoretical values, thus indicating the potential applicability of ( S )- 1a and related diketopiperazines as chiral solvating agents in NMR spectroscopy.

As an alternative to mechanical alloying, high temperature synthesis (HTS) of ultra-hard, super-abrasive AlMgB 14 was performed under normal pressure. The reaction mixture consisted of elemental aluminium and boron, whereas magnesium was added in the form of a Mg-precursor which liberates elemental magnesium approximately 400 °C above the melting point of magnesium, in this way reducing its evaporation during heating-up. The composition after the conversion was 95 wt.% of AlMgB 14 and 5 wt.% of MgAl 2 O 4 . The synthesized AlMgB 14 baseline powder, as well as mixtures of AlMgB 14 consisting of 30, 50 and 70 wt.% of TiB 2 , were hot pressed to near theoretical density. The various samples produced were characterized for microstructure and hardness. A micro-hardness of 29.4 GPa in hot pressed AlMgB 14 and a maximum Vickers hardness of 30.2 GPa in hot pressed samples of AlMgB 14 reinforced with 70 wt.% of TiB 2 were achieved.

Three vanadium compounds with β-diketonato or picolinato ligands were prepared and structurally characterized. In compounds [VO(tfpb)2]∞ (1) (tfpb = 4,4,4-trifluoro-1-phenylbutane-1,3-dionate) and [VO(acac)2(2-pyridone)] (2) the coordination of vanadium atom is octahedral and in the compound Hpy[VO2(pic)Cl] (3) the central atom is pentacoordinated. X-Ray crystallographic studies reveal infinite chain formation due to V=O···V=O interactions in 1, while 2 and 3 are mononuclear compounds. Centrosymmetric hydrogen-bonded dimers are formed in 2 via N–H···O interactions due to the 2-pyridone ligand. In 3 the Hpy+ cation is hydrogen bonded to the complex anion and crystal structure is further stabilized by π···π and C–H···O interactions.

The system Li—M—Y—BH4 (M: K, Rb, Cs) contains five new compounds, KY(BH4)4 (I), RbY(BH4)4 (II), Rb3Y(BH4)6 (III), Cs2Y(BH4)5 (IV), and Cs3Y(BH4)6 (V) which are characterized by synchrotron powder XRD, FTIR spectroscopy, impedance spectroscopy, and periodic DFT calculations.