Cage‐to‐Cage Cascade Transformations

A series of Pd₂ L ₄‐type binuclear self‐assembled coordination cages ( 1 – 4 ), where L stands for a nonchelating bidentate ligand, were prepared. The strategies adopted for the synthesis of the cages were: combination of Pd^II with 1) a selected ligand or 2) subcomponents of the ligand. Highly efficient cage‐to‐cage transformation reactions are demonstrated by suitable covalent modification (from 1 to 2 or 3 or 4 ) or ligand‐exchange reactions (from 1 to 2 or 3 or 4 ; from 2 to 3 or 4 ). Thus, new cascade transformations (from 1 to 2 to 3 ; from 1 to 2 to 4 ) are achieved beautifully.     

Synthesis of novel pyridocoumarins and benzo-fused 6-azacoumarins

Benzo[7,8]-fused 6-azacoumarins are prepared from 4-quinolinol by treatment with PPh₃ and DMAD, or from 3-formyl-4-quinolinol by Wittig reaction with carbalkoxyalkylidene(triphenyl)phosphoranes. Angular pyridocoumarins are prepared from 8- or 6-quinolinols with PPh₃ and DMAD, or from the reactions of 5,6- or 7,8-quinolinediones with carbalkoxymethylene(triphenyl)phosphoranes.     

Separations involving sulphides : Separation of bismuth,cadmium and indium from various other elements that form thiosalts

It has been shown that 2N sodium sulphide reagent can be successfully used in separating tellurium, molybdenum, antimony or rhenium from bismuth., platinum, gold, selenium, rhenium, arsenic, molybdenum or tellurium from cadmium; platinum, gold, selenium, rhenium, arsenic, molybdenum, tellurium or antimony from indium.It is not possible to separate quantitatively arsenic, platinum, gold or selenium from bismuth; antimony from cadmium; and tin from bismuth, cadmium or indium.     

Studies on the extraction and determination of metal salts with isobutyl methyl ketone-XIII Extraction of thorium and uranium

The work deals with the extraction of thorium or uranium from hydrochloric, perchloric, sulphuric or nitric acid solutions of various concentrations, or from mixed acid solutions, by means of isobutyl methyl ketone. When the extraction is made from 5-8M hydrochloric acid that is 10M in lithium chloride or from 7-8M hydrochloric acid that is 1M in magnesium chloride, uranium is extracted quantitatively (>99%), whereas thorium is hardly extracted at all.     

A New Route to Thio- and Selenosulfonates from Disulfides and Diselenides. Application to the Synthesis of New Thio- and Selenoesters of Triflic Acid

Alkyl and aryl trifluoromethanethiosulfonates(1) (or selenosulfonates) were prepared in one step either from alkyl and aryl sulfenyl (or selenenyl) chlorides and sodium trifluoromethanesulfinate (3) or, more generally, from disulfides (or diselenides), 3, and bromine. The second method involved trifluoromethanesulfonyl bromide as key intermediate. Benzenethiosulfonates were obtained in a similar way from disulfides, benzenesulfinate, and bromine but benzeneselenosulfonates could not be obtained by the same method from diselenides.     

Liposomal drugs dispersed in hydrogels. Effect of liposome, drug and gel properties on drug release kinetics

Release of calcein and griseofulvin (GRF) from control (gels in which solutes are dissolved in) and liposomal gels was studied using agarose-assisted immobilization as a technique to separate gels from drug-receptor compartments. Liposomes composed of phosphatidylcholine (PC) or distearoyl-glycero-PC and cholesterol (DSPC/Chol), and incorporating calcein or GRF were prepared by thin film hydration. After cleaning the liposomes they were dispersed in different hydrogels (carbopol 974 [1, 1.5 or 2% (w/w)], hydroxylethyl-cellulose (HEC) [4% (w/w)], or a mixture of the two), and release of calcein or GRF was followed by fluorescence or photometric technique, respectively. Results show that calcein release from liposomal gels is slower compared to control gels, and can be further retarded by using rigid-membrane liposomes (faster release from PC-liposome compared to DSPC/Chol-liposome gels). Additionally, calcein release is not affected by the lipid amount loaded (in the range from 2 to 8 mg/ml), therefore solute loading can be controlled according to needs.

Oppositely, GRF release from liposomal gels is determined by drug loading. At high drug loading levels (compared to GRF aqueous solubility), GRF is released with constant rate from liposomal gels irrespective of liposome type (PC or DSPC/Chol). Thereby, for amphiphilic/lipophilic drugs, drug properties (solubility, log P) determine the system behavior.

Calcein and GRF release from control carbopol gels is faster compared to HEC and mixture gels. The same is true for calcein in liposomal gels. Carbopol gel rheological properties were found to be significantly different (compared to the other gels), implying that these characteristics are important for drug diffusion from gels.     

Derivatization of Humic Compounds: An Analytical Approach for Bound Organic Residues

Abstract

Bound residues of pesticides and their metabolites are defined as being nonextractable with organic solvents, but partly extractable together with the humic matrix by NaOH or other solvents suitable to extract humic compounds. Recently, an improvement in humus extraction from soils was achieved upon derivatization of the organic matter with silylating reagents at room temperature. By this method 70–90% of the organic carbon or nitrogen either from soil or from humin became soluble in organic solvents. The extracts were analyzed by means of ¹³C NMR-spectroscopy. The spectra were well resolved with signal-separation of less than 1 ppm. The extracted humic compounds were of rather low molecular weight, ranging from 300 to 4000 to 6000 d or more.

¹⁴C-labeled residues of pesticides or other xenobiotics found to be nonextractable after exhaustive organic solvent extraction became readily dissolved along with most of the humic matrix using this derivatization procedure. Between 60–80% of ¹⁴C anilazine residues or of ¹⁴C-labeled chlorinated phenols or anilines originating from both previously solvent extracted soil samples or from humin became solubilized in organic solvents.     

Stereoselective hydrosilylation of enals and enones catalysed by palladium nanoparticles

A highly versatile and efficient hydrosilylation method by palladium nanoparticle catalysis allows the direct and chemoselective synthesis of 1) enolsilanes of high isomeric purity, 2) saturated aldehydes or ketones, or 3) the corresponding saturated acetals from α,β-unsaturated aldehydes or ketones. The choice of the product is determined by simply switching the solvent from THF to mixtures of THF/water or THF/alcohol.     

Functionalization and cyclization reactions of 4-benzoyl-1,5-diphenyl- 1H-pyrazole-3-carboxylic acid

The 1H-pyrazole-3-carboxylic acid 2 or its remarkably stable acid chloride 3 can easily be converted into the corresponding ester or amide derivatives 4 or 5, respectively, from reaction with alcohols or N-nucleophiles. Pyrazolo[3,4-d]pyridazines 6a,b are obtained from cyclocondensation reactions of the pyrazoles 2 and 3, respectively, with phenylhydrazine or hydrazine hydrate, while 6c is formed in an one-pot procedure from the furan-2,3-dione 1 and hydrazine hydrate.     

The use of modified acrylic copolymers for the preparation of immunoadsorbents

Summary Copolymer beads from acrylonitrile and ethyl either butyl acrylate or vinyl acetate, with amino, hydroxyl or carboxyl groups were activated with glutaraldehyde or water-soluble carbodiimide and coupled to human serum albumin. The obtained immunoadsorbents were applied to the isolation of anti-human albumin anibody from rabbit antiserum. Among the 22 studied copolymers only a few showed satisfactory effectiveness for immunoaffinity chromatography, similar to that noted for immunoadsorbents from commerical polymers.     

中国的百岁老人研究Ⅰ.百岁老人的地区分布、性别差异和民族特征

利用全国人口普查资料及部分地区的调查资料,统计分析了百岁老人的百岁比和性别比。结果显示,中国百岁老人存在明显的地区分布不均衡性、性别差异的可变化性,以及民族长寿的特异性。我国至少有4个省和自治区的百岁老人数男性多于女性,有13个民族的百岁老人比例达到联合国规定的长寿之乡标准,这些民族可称作长寿民族。     

Transformations of pyridiniums derived from amino-alcohols and from diamines : Novel ring closures

Pyridiniums derived from amino alcohols cyclise to ethers or rearrange to aldehydes on heating. Monopyridiniums from diamines can be acylated or converted into ureas or thioureas: these products cyclise on heating in solution to give dihydro-thiazoles, -4H-thiazines, -oxazoles, -4H-oxazines, or tetrahydro-3H-thiazepines.     

Skeletal rearrangements resulting from reactions of 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexopyranoses with diethylaminosulphur trifluoride

A complete series of eight 1,6:2,3- and 1,6:3,4-dianhydro-β-D-hexopyranoses were subjected to fluorination with DAST. The 1,6:3,4-dianhydropyranoses yielded solely products of skeletal rearrangement resulting from migration of the tetrahydropyran oxygen (educts of D-altro and D-talo configuration) or of the 1,6-anhydro bridge oxygen (D-allo, D-galacto). The major products yielded by the 1,6:2,3-dianhydropyranoses were compounds arising from nucleophilic substitution, with configuration at C4 either retained (D-talo, D-gulo) or inverted (D-manno), or from C6 migration (D-allo). The minor products in the 1,6:2,3-series resulted from migration of the tetrahydropyran oxygen (D-gulo) or the oxirane oxygen (D-manno), or from nucleophilic substitution with retention of configuration (D-manno). The structure of most of the rearranged products was verified by X-ray crystallography.     

Time-resolved ultraviolet laser-induced breakdown spectroscopy for organic material analysis

Ultraviolet pulses (266 nm) delivered by a quadrupled Nd:YAG laser were used to analyze organic samples with laser-induced breakdown spectroscopy (LIBS). We present characteristics of the spectra obtained from organic samples with special attentions on the emissions of organic elements, O and N, and molecular bonds CN. The choice of these atomic or molecular species is justified on one hand, by the importance of these species to specify organic or biological materials; and on the other hand by the possible interferences with ambient air when laser ablation takes place in the atmosphere. Time-resolved LIBS was used to determine the time-evolution of line intensity emitted from these species. We demonstrate different kinetic behaviors corresponding to different origins of emitters: native atomic or molecular species directly vaporized from the sample or those generated through dissociation or recombination due to interaction between laser-induced plasma and air molecules. Our results show the ability of time-resolved UV-LIBS for detection and identification of native atomic or molecular species from an organic sample.     

Resolvin D1, protectin D1, and related docosahexaenoic acid-derived products: Analysis via electrospray/low energy tandem mass spectrometry based on spectra and fragmentation mechanisms

Resolvin D1 (RvD1) and protectin D1 (Neuroprotectin D1, PD1/NPD1) are newly identified anti-inflammatory lipid mediators biosynthesized from docosahexaenoic acid (DHA). In this report, the spectra-structure correlations and fragmentation mechanisms were studied using electrospray low-energy collision-induced dissociation tandem mass spectrometry (MS/MS) for biogenic RvD1 and PD1, as well as mono-hydroxy-DHA and related hydroperoxy-DHA. The loss of H2O and CO2 in the spectra indicates the number of functional group(s). Chain-cut ions are the signature of the positions and numbers of functional groups and double bonds. The observed chain-cut ion is equivalent to a hypothetical homolytic-segment (cc, cm, mc, or mm) with addition or extraction of up to 2 protons (H). The alpha-cleavage ions are equivalent to: [cc + H], with H from the hydroxyl through a beta-ene or gamma-ene rearrangement; [cm - 2H], with 2H from hydroxyls of PD1 through a gamma-ene rearrangement, or 1H from the hydroxyl and the other H from the alpha-carbon of mono-HDHA through an alpha-H-beta-ene rearrangement; [mc - H], with H from hydroxyl through a beta-ene or gamma-ene rearrangement, or from the alpha-carbon through an alpha-H-beta-ene rearrangement; or [mm] through charge-direct fragmentations. The beta-ene or gamma-ene facilitates the H shift to gamma position and alpha-cleavage. Deuterium labeling confirmed the assignment of MS/MS ions and the fragmentation mechanisms. Based on the MS/MS spectra and fragmentation mechanisms, we identified RvD1, PD1, and mono-hydroxy-DHA products in human neutrophils and blood, trout head-kidney, and stroke-injury murine brain-tissue.     

Analysis of plasma-polymerized hydrocarbons by pyrolysis/gas chromatography

Plasma-polymerized oils, films and powders obtained from ethylene, acetylene, butadiene, and benzene were characterized by flash pyrolysis and gas chromatography (P/GC). None of the pyrograms resembled those of commercial polyethylene, polybutadiene, or polystyrene. Each of the plasma-polymer pyrograms did exhibit essentially the same fragments up to C₈, albeit in a different distribution, indicating that all samples are structurally similar. Analysis of the P/GC data shows these materials to contain a random arrangement of side chains, crosslinks, double bonds, and aromatic structures. Changes in the fragment distribution were obvious when the sample was a powder, solid film, or oily film produced from the same monomer. It was shown that powder products generally have a higher concentration of branches and/or crosslinks than the oil or film products. There are also differences in the pyrograms of products of the same form derived from dissimilar monomers. The results obtained from P/GC generally support those derived from infrared or NMR measurements performed earlier.     

A Comparison of the Efficiency of Nucleotide Extraction by Several Procedures and the Analysis of Nucleotides from Extracts of Liver and Isolated Hepatocytes by HPLC

Abstract

A high pressure liquid chromatography (HPLC) system was developed, capable of resolving most 5′-nucleotides and nucleotide-sugars present in liver tissue. Using three different extraction procedures, the recovery of the twelve major 5′-ribonucleotides from solutions of nucleotide standards, or liver samples, or isolated hepatocytes was compared. Nucleotides were obtained from acid extracts for HPLC analysis by adsorbing the nucleotides on charcoal, or precipitating the acid (perchloric acid) by KOH, or extracting the acid with alamine/ freon. The last two procedures were found to be superior to the charcoal adsorption procedure for recovering nucleotides from acid extracts. The recovery of nucleotides from either liver samples or isolated hepatocytes by these two procedures was similar; however, the recovery of nucleotides from standard solutions was slightly higher for the alamine/freon procedure than the KOH precipitation procedure.     

Synthesis of Isoquinoline-1, 3-Dicarboxylic Acid

Chiropticalluminescencemeasurementslhavebeenusedforstudyingchiralitydependentmolecularexcited-statedynamic,forstlldyingexcited-stateracemizationkineticsassociatedwithintermolecularchiralrecognitionprocessesinsolution2.Intheseprocesses,therearetwomolecularspecies,lanthanidecomplexes(luminophore)andresolvedtransitioncomplexes(AorA,quencher).Manykindsoftransitionmetalcomplexeshavebeenusedasquencherstoinvestigateinfluenceoftheintermolecularchiralrecognition.However,theluminophoreswereonlyconfined…     

Peculiarities of Thermochemical Investigations of Acid-Base Equilibria in Complexon Solutions

Polymorphic transitions of α-phenylcinnamic acid stereoisomers crystallized from various solvents (CHCl3, ethanol, diethyl ether), precipitated with different acids (acetic acid or HCl) or sublimed have been studied by differential scanning calorimetry (DSC). Measurements were also supplemented by powder X-ray diffractometry (XRD). Polymorphic transitions were not found for any of the E isomer samples irrespective of the method of treatment. However, in heating-cooling cycles reversible transitions could be detected for the Z isomer. On heating an exothermic peak was registered on samples sublimed, crystallized from ethanol or diethyl ether before melting, while samples precipitated by HCl or crystallized from chloroform exhibited more complex transitions. Here, endothermic effects were also observed. Enthalpy values for transformations (either for melting or polymorphic and other transitions) are also given. This revised version was published online in July 2006 with corrections to the Cover Date.