Unusual heterocyclization of chalcone podands with 3-amino-1,2,4-triazole

A new type of intramolecular cyclization of 1,5-bis[2-(E-3-oxo-3-phenylprop-1-enyl)-phenoxy]-3-oxapentane with 3-aminotriazole promoted by potassium ions was discovered. A cascade mechanism for the formation of crownophane with 4,7-dihydro[1,2,4]triazolo[1,5-a]-pyrimidine fragment was suggested. Effects of oligooxyethylene fragment of the chalcone podand and acid-base catalysis on the selectivity of the cyclocondensation processes and degree of oxidation of triazolopyrimidine fragments were studied. The product structures were confirmed by IR, ¹H and ¹³C NMR spectroscopy and X-ray diffraction study.     

Synthesis of Chiral Crownophanes Having Two Phenolic Groups via Tandem Claisen Rearrangement and Their Chiral Recognition

Asymmetric crownophanes having a chiral binaphthyl unit and two phenolic hydroxyl groups were thermally synthesized from the corresponding macrocyclic ethers via tandem Claisen rearrangement. Circular dichroism (CD) spectroscopic studies and HPLC experiments confirmed that little racemization of these crownophanes occurred during the thermal rearrangement. The association constants for the interaction of the chiral crownophanes with the enantiomers of phenylethylamine, phenylglycinol, and phenylalaninol were determined by a ¹H NMR titration method in CD₂Cl₂. As a result, the 27 membered crownophane has some chiral recognition for phenylglycinol.     

Synthesis,complexation, and supramolecular assembly of 21,30-dithia-17,25-dimethyl-1,4,7,10,13- pentaoxa[13.3.3](1,2,6)cyclophane

[structure: see text] A crownophane consisting of a dithia[3.3]metacyclophane moiety was synthesized by employing a high dilution method. The crystal structure and complexation behavior of this crownophane was studied. A hydrogen-bonded linear supramolecular assembly using anion-Na(+)-crownophane-solvent as a synthon was observed in the solid state. This supramolecular assembly was also stabilized via an intermolecular S.H-C interaction.     

Pre-organization of diarylideneacetonyl crownophanes in single crystals to photochemical transformations

Specific features of crystal packings and pre-organization of diarylideneacetonyl crownophane molecules to solid-phase photochemical transformations were studied on the basis of X-ray diffraction data using methods of simulation of molecular crystal packings. The tendency of the most part of the synthesized macrocyclic E,E-isomers to the formation of homochiral crystals (P2₁2₁2₁) was revealed, while (23E,26E)-11,12,14,15-tetrahydro-8H-dinaphtho-[2,1-k:1′,2′-r][1,4,7,10]tetraoxacyclononadecine-23,26-dien-25(9H)-one is prone to polymorphism. A phenomenon of solid-phase stereospecific photochemical dimerization of molecules according to the syn-head-to-tail type without crystal destruction (single crystal—single crystal transformation) was found for one of the modifications of this crownophane.     

Synthesis of a conformationally restricted polyoxygenated crownophane

A new polyoxygenated crownophane has been synthesized from syringaldehyde and diethyleneglycol by means of McMurry pinacol reaction, whereas ring closing metathesis with Grubbs’ catalyst failed in producing the macrocyclization to the corresponding stilbenophane. The NMR data of the crownophane show a restricted conformational space accessible to the phenyl rings.     

Wurster's thiacrown ethers: synthesis, properties, and Pt(II)-coordination chemistry

Two isomeric redox-responsive azathiacrown ethers, based on p-phenylenediamine, have been synthesized in traditional crown (L1) and crownophane (L2) architectures. Each of these "Wurster's crowns" was designed to target the encapsulation of transition or heavy metal ions. The solid-state structures of these ligands show binding cavities defined by three exocyclic sulfur atoms and either a N donor atom (L1) or the electron-rich pi face of the phenylenediamine subunit (L2). The ability of these ligands to form complexes with platinum(II) was investigated by various techniques including 1H NMR spectroscopy, electrospray mass spectrometry, cyclic voltammetry, and single-crystal X-ray analysis. The traditional crown geometry proved to be better at forming stable endocyclic complexes with Pt(II) than the crownophane geometry. The square-planar Pt(II) crown complex includes direct bonding to the redox center (Pt1-N1 = 2.125 angstroms and Pt1-S(av) = 2.278 angstroms) with concomitant polarization of the phenylenediamine moiety. This results in the crown complex oxidizing 916 mV more anodically than the free ligand. In contrast, modest shifts in the oxidation potential of the crownophane isomer indicate poor interaction between the redox center and complexed Pt(II) ion.     

Simultaneous Determination of Lonidamine, 1-(2,4-Dichlorobenzyl)-1h-indazole-3-carboxylic Acid,a New Antitumoral,and Its Impurity,N2 Substituted Isomer,by UV Derivative Spectrophotometry

Abstract

A direct and fast analytical method for the determination of Lonidamine and its impurity of synthesis, the N₂ alkylated isomer, by UV derivative spectrophotometry, is described.

The procedure was defined by regression analysis for a high number of standard solutions.

Linear relationships were obtained between mixture composition and maximum amplitude in <²D at 316 nm for Lonidamine quantitation, and peak trough ⁴D 226,234 and ⁴D 323,316 amplitudes by utilising polynomial equation for N₂ isomer quantitation.

The method, yielding accurate and precise results, was satisfactorily applied to laboratory mixtures and to a commercial formulation.     

Distribution of 210Po and 210Pb radionuclides and their dependence on physico-chemical parameters of soil in Madikeri taluk,Coorg district,Karnataka, India

The paper deals with distribution of ²¹⁰Po and ²¹⁰Pb radionuclides in a vertical profile of illuviated soil, in Madikeri taluk of Coorg district, Karnataka, India. The activity concentration of ²¹⁰Po and ²¹⁰Pb radionuclides was determined using radioanalytical method and the dependence of these radionuclides on physico-chemical parameters of soil was also investigated through a statistical study. In all the layers of the soil in a vertical profile, the ²¹⁰Po nuclides were found to be in disequilibrium with ²¹⁰Pb. The frequency distribution of ²¹⁰Po and ²¹⁰Pb radionuclides was analysed using Kolgomorov–Smirnov test.

     

Behavior of Zn,Cu, Pb and Cd in biota of Yangtze Estuary

The contents of zinc, copper, lead and cadmium were measured in the dominant species (plants:Scripus triquetor andPhrgrmites australis, macrobenthos:Ilyoplax deschampsin, Helice tridens tientsinensis, Bullacta exarata and Corbicula fluminea, and migrating waders: Calidris ruficollis and C. alpina) of the ecosystem of Yangtze Estuary, China, from 1995–1998. Results show that:

1. (1)

   Since the heavy metals stored in plants during growth seasons will be released into the environment in winter, plants are temporary stocks for metals. For the aboveground parts of reeds, about 156.6 kg·ha^-1·a^-1 of zinc, 369.9 kg·ha^-1·a^-10 of copper, 32.9 kg·ha^-·a^-1 of lead and 6.5 kg·ha^-1·a^-1 of cadmium were released.

2. (2)

   The mollusca, especially C.fluminea, are the key species storing and transporting heavy metals on the food chain.

3. (3)

   The temporal change in the highest trophic level was studied and found that it was significantly related with metabolic rates. The contents of heavy metals in Dunlin reach the peaks in January and October, which are wintering season and migratory season, respectively, of the bird.

4. (4)

   Organisms often show regulation/accumulation mechanisms to different elements of heavy metals. The elements that are widely required, such as zinc and copper, are accumulated at the metabolically active parts. It is quite another thing for the other two elements. Lead was regulated well and scarcely accumulated in the bodies of macrobenthos, but cadmium was absolutely accumulated in the animals.

5. (5)

   Heavy metals were found accumulated in some parts of the bodies of these organisms, such as shells and skeletons of macrobenthos and lives and muscles of waders.

6. (6)

   All these four elements were accumulated higher in the bodies of waders than in the plants and macrobenthos, which showed a bio-magnification function of the food chain. Overall, besides the physical and chemical processes, biological processes of heavy metal elements in Yangtze Estuarine ecosystem play a very important role in self-purification function of the ecosystem. Measurement of heavy metal contents in plants and animals in the estuarine ecosystem is an efficient technology for monitoring the environmental quality of the estuary.

     

Vinyl Polymerization. 269. Polymerization of Methyl Methacrylate Initiated by p,p'-Dimethoxydiphenyldiazomethane

Using p,p'-dimethoxydiphenyldiazomethane (DMDM) as initiator, the polymerization of methyl methacrylate (MMA) in benzene or in bulk was carried out. The initial rate of polymerization, R_p, was found to be expressed by the following equation:

R_p = k[DMDM]^0.53 [MMA]^0.84

The polymerization was confirmed to proceed by a radical mechanism. The over-all activation energy for the polymerization in benzene was calculated as 19.3 kcal/mole. The rate of thermal decomposition of DMDM was also measured in benzene and the rate equation was obtained as follows:

k_d (sec^?1) = 1.0 × 10¹⁵ exp (^?29.1 kcal/RT) (for 50-80°C)

Explanations of these observations are discussed in connection with those of the preceding papers.     

Synthesis,structures, and thermal properties of terpolymers of propylene oxide,carbon dioxide,and cyclohexene oxide

High molecular weight block terpolymers with different contents of polypropylene carbonate and cyclohexene carbonate units in the polymer chain were synthesized by the copolymerization of carbon dioxide, propylene oxide, and cyclohexene oxide. Zinc adipate was used as a catalyst. The terpolymerization products were characterized by ¹H and ¹³C NMR spectroscopy, IR spectroscopy, GPC, DSC, and DMA methods. The influence of the reaction conditions on the composition, microstructure, and molecular-weight and thermal characteristics was studied.

     

Determination du bore dans le zirconium,par activation au moyen de deutons

The determination of boron in zirconium by activation analysis using the¹⁰B(d, n)¹²C reaction with the chemical separation of¹¹C is described. The method was applied to industrial zirconium samples as zircalloy.

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Collaborateur temporaire de thèse au CEA.     

Darstellung von 4 t -Brom-1 c , 10 c -decalol und 4 t -Brom-1 c -methoxy-9 c , 10 c -decalin

The reaction of (Z, E)-1,5-cyclodecadiene with N-bromosuccinimide in the presence of water or methanol leads to transannular cyclizations producing 4 ^t -bromo-1 ^c , 9 ^c , 10 ^c -decalol, and 4 ^t -bromo-1 ^c -methoxy-9 ^c , 10 ^c -decalin, resp., in high yields. The stereochemistry of the products has been established by chemical methods, and NMR-techniques.

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Mit 1 Abbildung

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2. Mitt.:J. Graefe, G. Haufe undM. Mühlstädt, Z. Chem.16 180 (1976).

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Aus der Dissertation zur PromotionA. G. Haufe, Universität Leipzig, 1975.     

Terpolymerization of propylene oxide,carbon dioxide,and trimethylene carbonate

High-molecular-weight polymers with different contents of propylene carbonate (PC), and trimethylene carbonate (TMC) units in the polymer chain were synthesized by the coordination anionic copolymerization of carbon dioxide, propylene oxide (PO), and TMC in supercritical carbon dioxide (scCO₂). Zinc adipate (ZnAd) was used as a catalyst. The terpolymerization products were characterized by ¹H and ¹³C NMR, IR spectroscopy, GPC, and DSC. The effect of the reaction conditions on the yield, composition, structure, and molecular weight and thermal characteristics of the terpolymers was studied. The phase behavior of the synthesized polymers and mixtures of polypropylene carbonate with polytrimethylene carbonate was examined.

     

Determination of Cytochrome C,in Solution and in The Adsorbed State,by Differential Pulse Voltammetry (DPV).

Abstract

We carried out the determination of cytochrome C, in solution and in the adsorbed state, using differential pulse voltammetry (DPV). The results obtained with DPV were compared with those obtained using cyclic voltammetry (CV). The influence of the nature of the electrodic material and of the different promoters was shown. It was also demonstrated that the electron transfer in solution and in the adsorbed state is quasi-reversible.

Cytochrome C was determined at a concentration of 1.0 × 10^?5 mol L^?1 which was more one decade lower than that obtained by cyclic voltammetry. The linearity range was more than two decades.     

Simultaneous LC Analysis of Aloe-Emodin,Rhein, Emodin,and Chrysophanol in Rhizoma Rhei-Type Preparations

A simple and sensitive liquid chromatographic method has been established for simultaneous analysis of four compounds (aloe-emodin, rhein, emodin, and chrysophanol) in Rhizoma Rhei-type preparations. The compounds were separated in less than 20 min on a C₁₈ column with 70:30 methanol–0.2% aqueous acetic acid as mobile phase at a flow rate of 1 mL min⁻¹. The method was validated for specificity, accuracy, precision, and limits of detection. Good linear regression data (r ² > 0.9980) were obtained for all the calibration plots within the ranges tested. The method is an attractive alternative for evaluation of the quality of Rhizoma Rhei-type preparations.

     

A bis(rhodamine 6G)-based fluorescent sensor for Hg2+: microwave-assisted synthesis,photophysical properties,and computational studies

A fluorescent and colorimetric sensor based on rhodamine 6 g (RD6g) was designed, synthesized, and characterized using microwave irradiation. The sensing behavior of this compound was studied by UV–visible and fluorescence spectroscopy. Sensor RD6g exhibits a high selectivity and an excellent sensitivity and is a dual-responsive colorimetric and fluorescent Hg²⁺-specific sensor in aqueous buffer solution. Mercury ions give rise to the development of a very fluorescent ring-open amide spirolactam system. The detection limit for Hg²⁺ was found to be 1.2?×?10^?8 M. The binding ratio of RD6g-Hg²⁺ complex was determined to be 1:1 according to the Job’s plot. The reversibility of RD6g?Hg²⁺ complex has been achieved with CN^? anions. The test strip based on RD6g was developed, which could be used as a suitable and methodical Hg²⁺ test kit.

     

LC-MS-MS Determination of (S,R)-Penehyclidine in Rat Plasma

A sensitive and selective method for determination of (S,R)-penehyclidine in rat plasma by liquid chromatography-tandem mass spectrometry is described. The procedure employed the use of an internal standard (I.S.) and a simple protein precipitation step. The method developed was linear from 0.1 to 100 ng mL⁻¹, with a sensitivity of 0.1 ng mL⁻¹ as the lower limit of quantification. The intra- and inter-day assay accuracy (relative error) was within 8.27% and precision (RSD) was below 6.7%. It was successfully applied to pharmacokinetic studies of (S,R)-penehyclidine in rat plasma.

     

Synthesis and properties of non-symmetrical phosphor(ɪɪɪ)arene macrocycle based on 4,4′-iminodiphenol, 4,4′-methylenediphenol,and phenylphosphonic acid tetraethyldiamide

Binuclear non-symmetrical phosphor(???)arene macrocyclic phosphonite bearing different aromatic fragments (Ar¹ ≠Ar²) was synthesized using two different bisphenols (4,4′-iminodiphenol and 4,4′-methylenediphenol) as the starting material. The characteristic properties of the synthesized macrocycle that confirm its structure, in particular, oxidation and sulfurization reactions, were studied.

     

Synthesis,Characterization, and Activity of Cyclotriphosphazene-Cyclene Conjugates

Abstract

Two novel cyclotriphosphazene derivatives were synthesized from hexachloro cyclotriphosphzene. Their structures were characterized by ¹H, ³¹P, and ¹³C NMR spectroscopy as well as by IR spectroscopy and electrospray ionization-mass spectrometry (ESI-MS). The Zn complex of 4d was effective in hydrolytic DNA cleavage reactions.