Synthesis and characterization of some <Emphasis Type="Italic">o</Emphasis>,<Emphasis Type="Italic">o</Emphasis>′-dihydroxyazo dyes and their metal complexes

The synthesis and characterization of azo dyes containing o,o′-dihydroxy groups and their azo-metal(II) [Cu, Co, Ni, Zn] chelates by ¹H N.M.R., IR, AAS, UV–VIS, magnetic susceptibility and thin-layer chromatography techniques are reported. The stochiometry of the azo-metal chelates was determined by the spectroscopic titration method to be 1:2 (ML₂). The synthesized azo dyes and azo-metal chelate dyes were applied on wool fabric. Fastness to light and washing were measured.     

<Emphasis Type="Italic">β</Emphasis>-Chloro-<Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">β</Emphasis>-unsaturated carbonyls as convenient precursors of highly substituted benzenes

The Diels–Alder reactions of three β-chloro-α,β-unsaturated carbonyl compounds 1–3 with different dienes were carried out to afford highly functionalized cyclohexenes 4–9, bearing quaternary centers, in good yields. These cycloadducts (CAs) undergo dehydrochlorination with subsequent aromatization in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene DBU to produce new substituted benzenes 11–14. Compound 10 is the product of lactonization and removal of an HCl molecule from compound 7. All products were characterized by NMR, IR, elementary analysis and some of them by MS. Structure assignments of isomers were carried out on the basis of NMR chemical shifts and coupling constants using 1D, 2D and heteronOe NMR techniques.     

Novel mixed-ligand complexes of coumarilate/<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>′-diethylnicotinamide with some transition metals

Coordination complexes of transition metal cations (Co^II, Ni^II, Cu^II and Zn^II) containing coumarilate and N,N′-diethylnicotinamide were synthesized. The structural characterization and thermal behaviour analysis of novel samples synthesized were conducted through elemental analysis, magnetic susceptibility, solid-state UV–Vis, direct and injection probe mass spectra, FTIR spectra, thermoanalytic TG-DTG/DTA and single crystal X-ray diffraction methods. The structural details of single crystals of [Co(dena)₂(H₂O)₄](coum)₂ (I) and [Cu(coum)₂(dena)₂(H₂O)₂] (III) complexes were resolved completely. Moreover, the results of analysis obtained for [Ni(coum)₂(dena)₂(H₂O)₂] (II) and [Zn(dena)₂(H₂O)₄](coum)₂ (IV) complexes were interpreted considering the samples with crystal structures defined and made assumptions about the structural details. It was determined that the complex of Co^II metal cation has salt-type structure and the coordination number of metal is accomplished to six as the sum of 4 mol of water and also 2 mol of N,N′-diethylnicotinamide ligands in trans position located within the coordination sphere. It was observed that 2 mol of coumarilate anions are located outside the coordination sphere and have stabilized to the charge (2+) of metal. The Cu^II complex has totally molecular structure, and the coordination sphere of metal cation was 6 as the sum of 2 mol of water, 2 mol of N,N′-diethylnicotinamide and 2 mol of monoanionic monodentate coumarilate ligands. All ligands have been located in –trans position. The geometry of both complex structures is distorted octahedral. It is assumed that the Ni^II complex structure is isostructural with Cu^II complex structure and also does Zn^II complex with Co^II structure. It was determined that the decomposition products obtained from thermal analysis are the oxides of related metal cations.     

Enantioseparation of Hydrobenzoin and Structurally Related Compounds on <Emphasis Type="Italic">β</Emphasis>-Cyclodextrin and Hydroxypropyl-<Emphasis Type="Italic">β</Emphasis>-cyclodextrin Bonded Chiral Stationary Phases

A β-cyclodextrin (β-CD) and a hydroxypropyl-β-cyclodextrin (HP-β-CD) bonded chiral stationary phase (CSP) were prepared. Comparative evaluations of these two CSPs for the enantioseparation of hydrobenzoin, benzoin and α-phenethyl alcohol by reversed-phase liquid chromatography were presented. The effects of buffer composition in the mobile phase on the retention and enantioseparation were investigated. The borate buffer had a significant influence on the retention and enantioseparation of hydrobenzoin. Linear solvent strength retention model was used to fit the chromatographic data. Good linearity existed between the logarithm of retention factor (k) and the volume fraction of organic modifier (φ). Another retention model, stoichiometric displacement theory for retention, was also tried to fit the chromatographic data. The results showed that not only acetonitrile, but also water molecules participated in the displacing process of the solute.     

Spectroscopic and electrical characterization of <Emphasis Type="Italic">α</Emphasis>,<Emphasis Type="Italic">γ</Emphasis>-bisdiphenylene-<Emphasis Type="Italic">β</Emphasis>-phenylallyl radical as an organic semiconductor

The semiconductor properties of the earliest known stable radical, α,γ-bisdiphenylene-β-phenylallyl radical (Koelsch radical, 1^?) were assessed using spectroscopic and electrical techniques. This radical undergoes reversible redox processes, and it has low redox potentials. In addition, 1^? possesses long wavelength absorption bands, owing to the existence of a singly-occupied molecular orbital whose energy level lies between those of the HOMO and LUMO. A spin-coated thin-film of 1^? displays photocurrent and an electron mobility of 6.3 × 10^?7 cm² V^?1 s^?1 on a trially-fabricated organic field effect transistor.     

Release profiles of indometacin in <Emphasis Type="Italic">β</Emphasis>-cyclodextrin complexes from HPMC capsules

Powders containing indometacin complexed with β-cyclodextrin (1:1 ratio) obtained by two complexation methods (suspension/solution [with water removed by air stream, spray– and freeze–drying] and kneading techniques) were compared between them to observe the increase on the drug solubility and yield of the complexation process. The tests used for this comparison included the determination of the moisture content, true and bulk densities, angle of repose, Carr’s index and in vitro drug release (at pH 1.0) from HPMC capsules. In the dissolution tests the drug release was analyzed considering different parameters (similarity factor (f ₂), dissolution efficiency (DE) and the amounts released (M _t) at certain times (30, 60 and 180 min) by statistic analysis (α = 0.05)). The results obtained showed poor pharmaceutical properties for all mixtures and that the indometacin released from capsules containing inclusion complexes presented an increase on solubility when compared with reference formulation (lactose and microcrystalline cellulose instead of β-cyclodextrin). The release of indometacin showed no dependency on the amount of water used in the formation of the complexes being the differences observed mostly due to the characteristics of the particles, which were dependent on the complexation method. However the low yield of the complexation that occurred can be explained by the difference between the size of the drug molecule, the guest (diameter—7.5 Å, length—14.2 Å) and the size of the β-cyclodextrin cavity, the host (diameter—6.0–6.5 Å).     

<Emphasis Type="Italic">N</Emphasis>′-tetrazolylmethoxyl derivatives of <Emphasis Type="Italic">N</Emphasis>-methyldiazene <Emphasis Type="Italic">N</Emphasis>-oxides

A preparation method was developed for previously unknown tetrazole derivatives containing in the 1, 2, and/or 5 positions of the tetrazole ring N-methyldiazene-N-oxide-N′-oxymethyl groups.     

An efficient synthesis of <Emphasis Type="Italic">β</Emphasis>-methoxycarbonyl-<Emphasis Type="Italic">γ</Emphasis>-butyrolactones

β-Methoxycarbonyl-γ-butyrolactones bearing a γ-aromatic substituent were prepared via copper-catalyzed reductive aldol addition/lactonization domino reactions of ketones with α,β-unsaturated dicarboxylate esters and a silane under ambient temperature. The reaction has advantage of using readily available reagents, mild conditions and high efficiency.     

Theoretical and experimental NMR studies of the Swern oxidation of methyl 6<Emphasis Type="Italic">α</Emphasis>,7<Emphasis Type="Italic">β</Emphasis>-dihydroxyvouacapan-17<Emphasis Type="Italic">β</Emphasis>-oate

This work describes the synthesis of new derivatives of 6α,7β-dihydroxyvouacapan-17β-oic acid (1) employing the Swern method for the oxidation of C-6 and C-7 of methyl 6α,7β-di-hydroxyvouacapan-17β-oate (2) and the formation of methyl 6,7-dioxovouacapan-17β-oate (3). NMR structural studies associated with theoretical calculations of reaction intermediates and products are also reported. The mixture of methyl 7β-hydroxy-6-oxovouacapan-17β-oate (4; 21%) and methyl 6α-hydroxy-7-oxovouacapan-17β-oate (5; 79%) was the product from the first step of the oxidation of 2. The lower energy of 5, calculated by HF/6-31G* and DFT/BLYP/6-31G* methods, reinforces the thermodynamic control proposed for the reaction. After further Swern oxidation of the mixture of 4 and 5, the isomeric form methyl 6-hydroxy-7-oxovouacap-5-en-17β-oate (6) was obtained. Theoretical calculations indicate a lower energy for the mono-enol 6 than the 1,2-diketo 3 and the other mono-enol methyl 7-hydroxy-6-oxovouacap-7-en-17β-oate (7).     

Inclusion complexes of <Emphasis Type="Italic">p</Emphasis>-hydroxybenzoic acid esters and γ-cyclodextrin

The alkyl esters of p-hydroxybenzoic acid (parabens) are commonly used as preservatives in cosmetics, food products and pharmaceutical formulations because of their wide range antimicrobial activity. However, the usage of parabens in aqueous media has been hampered, especially parabens with long alkyl chains, due to their low aqueous solubility. One approach to increase their solubility is cyclodextrins (CDs) complexation to form water-soluble inclusion complexes. γCD has the widest hydrophobic central cavity and the highest water solubility among natural CDs. Hence, inclusion complexes between γCD and parabens of various alkyl chain lengths were investigated. Results from phase-solubility studies show that methyl- and ethylparaben form various complexes of paraben/γCD (i.e. 1:1, 2:1, etc.) while the 1:1 complex was dominant in propyl- and butylparaben/γCD complex solution. Moreover, the effect of the paraben complexation on the critical aggregation concentration (cac) of γCD in aqueous solutions was determined. It was found that the longer the paraben alkyl chain was the more influence it had on the γCD cac. In pharmaceutical formulations the mixture of parabens (i.e. binary, ternary and quaternary) has been used to maximize antimicrobial effect. It is important to determine how mixtures of parabens affect the solubility of γCD and its cac values upon formation of inclusion complexes. Competition of the different parabens for a space in the γCD central cavity was evaluated by comparing the γCD cac values obtained in presence of the individual parabens and their mixtures.     

Thermophysical properties of <Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dimеthylacetamide mixtures with <Emphasis Type="Italic">n</Emphasis>-butanol

The refraction, dielectric, viscosity, density, data of the binary mixtures of N,N-dimethylacetamide (DMA) with n-butanol at 308.15 and 313.15 K. The measured parameters used to obtain derived properties like Bruggeman factor, molar refraction and excess static dielectric constant, excess inverse relaxation time, excess molar volume and excess viscosity, excess molar refraction. The variation in magnitude with composition and temperature of these quantities has been used to discuss the type, strength and nature of binary interactions. Results confirm that there are strong hydrogen-bond interactions between unlike molecules of DMA+ n-butanol mixtures and that 1: 1 complexes are formed and strength of intermolecular interaction increases with temperature.     

10<Emphasis Type="Italic">α</Emphasis>-Hydroxy-<Emphasis Type="Italic">β</Emphasis>-isomorphine,a by-product of the synthesis of 10<Emphasis Type="Italic">α</Emphasis>-hydroxymorphine

Abstract  A new compound was isolated from the reaction mixture after O-demethylation of 6-O-acetyl-10α-acetoxycodeine with boron tribromide. The structure of this compound, 10α-hydroxy-β-isomorphine, was elucidated by spectral data, and its spatial arrangement was deduced from an NOE experiment. Capillary zone electrophoresis was used for separation of morphine and its 10-hydroxy analogues. Graphical abstract        

Temperature-dependent <Emphasis Type="Italic">β</Emphasis>-crystal growth in isotactic polypropylene with <Emphasis Type="Italic">β</Emphasis>-nucleating agent after shear flow

In our current work, the effect of the shear temperature on the growth of β-crystal in isotactic polypropylene (iPP) with β-nucleating agent is investigated by means of in situ two-dimensional wide-angle X-ray diffraction (2D-WAXD). At low shear temperatures, the formed shear-induced oriented precursors are hard to relax back to random coiled state due to the weak mobility of molecular chains. Therefore, plenty of oriented α-crystals are induced by shear-induced oriented precursors, while β-crystal is greatly depressed. As the shear temperature increases, oriented β-crystal gradually increases along with the decrease of α-crystal. It is deduced that the shear temperature at which the content of β-crystal increases to the (maximum) value found in quiescent crystallization is almost the same as that at which the accelerating effect of flow on crystallization kinetics is completely erased. Our work manifests its significance in regulating β-crystal and thus in the structure and property manipulation of iPP.     

New heteroscorpionate lanthanide complexes for ring-opening polymerisation of <Emphasis Type="Italic">ε</Emphasis>-caprolactone and <Emphasis Type="Italic">rac</Emphasis>-lactide

Yttrium and lanthanum amido-complexes with bis(pyrazol-1-yl)acetates in their coordination spheres were studied as the catalysts in ε-caprolactone and lactide ring-opening polymerisation. A high molecular mass poly(ε-caprolactone) (PCL) was obtained in almost quantitative yield under mild conditions. rac-Lactide polymerisations were less efficient and required quite harsh experimental conditions to obtain atactic PLA samples with moderate yields. The average chain-length of PCL was dependent upon the choice of the metal centre and the presence of substituents on the pyrazole rings of the ancillary ligand. The ground-state geometries of the complexes and the first stages of ε-caprolactone polymerisation were computationally modelled by means of DFT calculations.     

Extraction-photometric determination of <Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-dialkylbenzhydrazides as its complexes with copper

A procedure for extraction-photometric determination of N′,N′-dialkylbenzhydrazides has been proposed; the procedure is based on the formation of its colored complex with copper (II) followed by extraction with p-xylene and absorbance measurements at 460 nm (0.1–0.4 mmol of analyte in the sample) or at 330 nm (0.005–0.025 mmol of analyte in the sample).     

Allylic oxidation of 19<Emphasis Type="Italic">β</Emphasis>,28-epoxy-a-neo-5<Emphasis Type="Italic">β</Emphasis>-methyl-25-nor-18<Emphasis Type="Italic">α</Emphasis>-olean-9-ene

Allylic oxidation of 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-ene by ozone produced 19β,28-epoxy-A-neo-5β-methyl-25-nor-18α-olean-9-en-1-one.     

Synthesis of lupane and 19<Emphasis Type="Italic">β</Emphasis>,28-epoxy-18<Emphasis Type="Italic">α</Emphasis>-oleanane 2,3-<Emphasis Type="Italic">seco</Emphasis>-derivatives based on betulin

The α-hydroxyoximes of methyl betulonate and allobetulone were synthesized. Beckmann fragmentation of them produced the lupane and 19β,28-epoxy-18α-oleanane 2,3-seco-derivatives. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 491–494, September-October, 2008. Original article submitted July 4, 2008.     

Complex formation of magnesium and calcium ions with trimethylenediamine-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>’,<Emphasis Type="Italic">N</Emphasis>’-tetraacetic acid

Stability constants and heat effects of the formation reactions of magnesium and calcium trimethylenediaminetetraacetates at 298.15 K and ionic strength of 0.1, 0.5, and 1.0 (mol/L KNO₃) have been determined by means of potentiometry and calorimetry. Standard thermodynamic parameters (log K⁰, Δ_rG⁰, Δ_rH⁰, and Δ_rS⁰) of the studied equilibriums have been determined.