On the formation of water-soluble buckminsterfullerene-γ-cyclodextrin complexes

Abstract

γ-Cyclodextrin appears to catalyze the reaction of C₆₀ with water during reflux and in addition to the water soluble 1:1 and 2:1 complexes (whose stability constants could be estimated as ≥ 4 × 10² and ≥ 4 × 10⁴, respectively) some (complexed) fullerene derivatives are also formed.     

Simultaneous determination of levofloxacin hemihydrate and ambroxol hydrochloride in tablets by thin-layer chromatography combined with densitometry

This paper describes the application of thin-layer chromatography (TLC) combined with densitometry to simultaneous determination of levofloxacin hemihydrate (LEV) and ambroxol hydrochloride (AMB) in bulk and tablets. The separation was achieved on aluminum sheet of silica gel 60 F ₂₅₄ using chloroform: methanol: toluene: ammonia (10: 6: 3: 0.8 v/v/v/v) as mobile phase. Quantification was carried out densitometrically at 245 nm. This system was found to give compact spots for LEV (R _f value of 0.4) and AMB (R _f value of 0.7). The calibration curves for LEV and AMB was found to be linear between 9960–16600 ng/spot (r ² = 0.999) and 600–1000 ng/spot (r ² = 0.999), respectively. The mean percentage recoveries from tablets for LEV and AMB were 99.45% and 99.58%, respectively. The TLC-densitometry method has many advantages, such as simplicity, reasonable sensitivity, rapidity, and low cost, and it can be successfully used in routine analysis of both these drugs in tablet formulations.     

Two new clerodane-type diterpenoids from Bornean liverwort Gottschelia schizopleura and their cytotoxic activity

The Bornean liverwort Gottschelia schizopleura was investigated phytochemically for the first time. Two new and four previously known clerodane-type diterpenoids were isolated from the MeOH extract of G. schizopleura through a series of chromatographic techniques. The structures of the new metabolites were established by analyses of their spectroscopic data (1D NMR, 2D NMR, HRESIMS and IR). All the isolated compounds 1–6 were tested against human promyelocytic leukaemia (HL-60), human colon adenocarcinoma (HT-29) and Mus musculus skin melanoma (B16-F10). Compound 1 and 2 showed active inhibition against HL-60 and B16-F10 cells.     

Synthesis and antitumor activity of camptothecin- 4β-triazolopodophyllotoxin conjugates

Abstract

Two new compounds (9 and 10) having a camptothecin (CPT) analog conjugated to the 4β-azido-4-deoxypodophyllotixin analog by untilizing the copper-catalyzed azide-alkyne cycloadditon (CuAAC) reaction, and were evaluated for their cytotoxicity against a panel of five human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) using the MTT (3-(4,5-dimethyl-thiahiazo-2-yl)-2,5-diphenyltetrazolium bromide) assay. Two novel conjugates shown weak cytotoxicity, compound 10 showed highly potent against HL-60 cell line tested, with IC₅₀ value 17.69?±?0.19?μM. This compound suggested its potential as anticancer agents for further development.

     

Coordination interactions in the crystalline lattice of alkaline ions with the polyoxometalate [V12B18O60H6]10− ligand

In the present work, the synthesis and structural characterization of two new polyoxovanadoborate (BVO) frameworks, based on the [V₁₂B₁₈O₆₀H₆]^10? polyanion, are reported, K(H₃O)(enH₂)₄[V₁₂B₁₈O₆₀H₆]·9.60H₂O (1) and Li₈(NH₄)₂[V₁₂B₁₈O₆₀H₆]·8.02H₂O (2). Both compounds are obtained in a mixed valence ratio of 10V^IV/2V^V. Framework 1 is characterized by potassium ions coordinated by the BVO cluster and ethylenediammonium and hydronium ions as charge-compensating agents. In framework 2, the BVO clusters are coordinating lithium ions and the charge is compensated by ammonium ions. Using the SHAPE 2.1 program, it was possible to calculate the best geometry for the existing lithium and potassium ions. For 2, the lithium ions are five-coordinate, best described by a square pyramid (SPY-5), while the coordination sphere around the potassium ions in 1 are six-coordinate. For 1, the coordination sphere of the existing potassium ions in the framework can be described as trigonal prism (TPR-6). Calculations were also done for a previously reported cluster [Na₁₀[(H₂O)V₁₂B₁₈O₆₀H₆]·18H₂O] (3), in which the sodium ions are six-coordinate but in two different geometries, these being octahedral and TPR-6. The influence of the interactions of the alkali ions with the [V₁₂B₁₈O₆₀H₆]^10? polyanion, on the vanadate and borate absorption bands observed in the infrared spectra, is discussed.     

Synthese von Benzofuranen durch Cyclodehydrierung von Phenylmalonylheterocyclen

Phenylmalonyl heterocyclic compounds such as the quinolones1a–c or3, benzoquinolizinones6a, b and the phenalenones8a, b can be converted to benzofuranes (2a–c, 7a, b and9a, b) by cyclodehydrogenation with Pd/C in boiling diphenyl ether. 2-Phenylchinchonic acid (10) reacts under the same conditions to the dimeric benzofuroquinoline12: the decarboxylated quinoline11 however gives the monomer13.

Herrn Prof. Dr.G. Zigeuner zur Vollendung seines 60. Lebensjahres gewidmet.     

The reaction of ethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate with fullerene C60

Heating (100 °C, toluene) or photolysis (Nd³⁺ : YAG laser, = 532 mil, benzonitrile) of a mixture of ethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate (Hantsch ester) (1) and fullerene C₆₀ under anaerobic conditions results in the formation of fullerene hydrogenation products and ethyl 2,6-dimethylpyridine-3,5-dicarboxylate, which is the product of dehydrogenation of1, identified by IR spectroscopy and mass spectrometry. The triplet state of C₆₀ is quenched by the Hantsch ester.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2531–2534, October, 1996.     

6-氨基己酸及2-氨基乙磺酸C60加成物的合成及溶解性

水溶性Fullerenes (C₆₀)衍生物的制备对于C₆₀的生物学研究具有十分重要的意义. 氨基酸与C₆₀的胺化反应可得到水溶性的氨基酸C₆₀衍生物. 以C₆₀与过量6-氨基己酸或2-氨基乙磺酸(摩尔比为1∶10)于80 ℃搅拌反应24 h, 分别得到加成度为5和4的氨基酸C₆₀主产物, 产率按加入的C₆₀计算分别为30%, 28%. 氨基酸碳链的长度及加成产物在反应体系中能否及时沉淀析出影响和控制着加成度的大小. C₆₀[NH(CH₂)₅COOH]₅H₅ (3a), C₆₀(NHCH₂CH₂SO₃H)₄H₄ (6a)用柱层析进一步纯化, 其结构组成经元素分析, ¹H NMR, ¹³C NMR, IR所证实. 6a的水溶性受溶液pH的影响较小, 3a在不同pH缓冲溶液中的溶解性用光谱法测定, 分别为: pH＝10.25时为71.81 mg•mL^－1, pH＝7时为23.68 mg•mL^－1, pH＝3.36时为10.12 mg•mL^－1. 在波长273 nm处, 3a的摩尔消光系数为ε＝3.43×10⁴ L•mol^－1•cm^－1.     

Stoffwechselprodukte von Actinomyceten

Ohne ZusammenfassungMit 1 AbbildungHerrn Prof. Dr.F. Wessely zum 60. Geburtstag gewidmet.10. Mitt.: Helv. Chim. Acta40, 1768 (1957).     

Cytotoxicity and Synergistic Effect of the Constituents from Roots of Aglaia odorata (Meliaceae)

Twelve compounds were isolated from the roots of Aglaia odorata. Their structures were established on the basis of NMR and MS data as rocaglaol (1), rocaglamide (2), eichlerialactone (3), sapelins A (4), isofouquierone (5), eichlerianic acid (6), shoreic acid (7), agladupol E (8), 3-epimeliantriol (9), cleomiscosins B (10), 2β,3β-dihydroxy-5α-pregnane-16-one (11) and β-d-glucopyranos-1-yl N-methylpyrrole-2-carboxylate (12). Among them, compounds 1 and 2 showed significant cytotoxicity against human cancer cell (HL-60, SMMC-7721, A-549, MCF-7 and SW480) with IC₅₀ values of 0.007–0.095 μM, while compounds 3–5 and 10 and 11 showed moderate to no cytotoxicity (IC₅₀ 0.43 to values >40 μM). Compound 6 showed only weak cytotoxicity (IC₅₀ 6.87 to >40 μM) and its epmier 7 was completely inactivite (IC₅₀>40 μM) in the assay. However, potent synergistic effect was observed when the molar ratio of 6 to 7 is between 4:1 and 1:1.     

Copper(II) complexes of two TEMPO-functionalized polypyridyl ligands: structure and catalytic activity in alcohol oxidation

The reaction of copper(II) salts with Bpy-TEMPO and Tpy-TEMPO (Bpy-TEMPO = [2,2′]Bipyridinyl-5,5′-dicarboxylic acid bis-[(2,2,6,6-tetramethyl-1-oxy-piperidin-4-yl)-amide]; Tpy-TEMPO = 2,2,6,6-tetramethyl-4-(2,2′:6′,2″-terpyridin-4′-yloxy)piperidin-1-oxyl) gave dinuclear Bpy-TEMPO-Cu₂ (1) and mononuclear Tpy-TEMPO-Cu (2), respectively. The Cu(II) complexes were characterized by single crystal X-ray analysis. In 1, Cu(II) has a distorted square pyramidal coordination geometry, with a bridging chloride as the axial ligand. The Cu(II) core in 2 also exhibited a distorted square pyramidal coordination geometry, with one chloride as an axial ligand. Weak interactions such as π-interactions and hydrogen bonds are observed in both complexes. When applied as catalysts for the oxidation of benzyl alcohol to benzaldehyde in air, 1 exhibited higher activity than 2 for reactions in o-xylene at 60°C with DBU as a base. High yield (67%) of benzaldehyde was observed when using 1 as a catalyst in a solution of o-xylene with DBU at 60°C.     

High-Performance Liquid Chromatography of Copper,Mercury, Nickel,and Cadmium Bisdibenzyldithiocarbamate Complexes

Abstract

High-performance liquid chromatographic separations of Cu (II), Hg(II), Ni(II), and Cd(II) bisdibenzyldithiocarbamates at nanogram levels by adsorption chromatography on silica gel were reported. Lichrosorb Si 60 (10 um) was used as the stationary phase and benzene-cyclohexane mixtures as the mobile phase.     

1,3-Dipolar cycloadditions of heterocycles 1. Cycloadditions ofC-benzoyl-N-phenylnitrone to furan

A frontier orbital treatment of furan suggests its possible reactivity in 1,3-dipolar cycloadditions with dipoles posessing low lying LUMO's, such as nitrones, especially those with electronwithdrawing substituents. By the reaction ofC-benzoyl-N-phenylnitrone1a with an excess of furan at 60° the monocycloadduct2a, two biscycloadducts4 and5 and further reaction products of nitrone such as azoxybenzene8, diketoamide9a, benzoanilide10a, benzoic acid11a and phenyl glyoxylic acid12 were isolated. The cycloaddition ofC-(4-bromobenzoyl)-N-phenylnitrone1b with furan is also reported.Part CXXXVI in the series Furan Derivatives; Part CXXXV: Coll. Czech. Chem. Commun., in press.     

High-Molecular-Weight Alternating Copolymers from Thermal Copolymerizations of N-Alkylcitraconimides with Styrene

Radical copolymerizations of eight N-alkylcitraconimides (1) and styrene (2) were carried out in the presence or absence of a radical initiator. Alternating copolymers with number-average molecular weights higher than 7 × 10⁵ were obtained from the thermal copolymerizations (monomer molar ratio = 1:1) in bulk at 60°C. The spontaneous copolymerization is considered to be by induced radicals produced via an intermediate Diels-Alder dimer and minary a contact-type charge transfer complex between N-alkylcitraconimide and styrene. Thermogravimetric analyses indicate the resulting copolymers have high thermal stabilities.     

Thallium(I) Selective Solid Membrane Electrode

Abstract

Heterogeneous membranes of 2.0 cm diameter were prepared from a 60:40 mixture of thallium(I) molybdoarsenate and Araldite, These membranes gave near Nernstian response to thallium(I) ions over the concentration range 10^?1 to 10^?3M but could be used for determination of thallium(I) down to 10^?5M. Slope of the log concentration-potential plot is improved in 10 and 25 percent acetone-water mixture. The response was independent of pH over the range 4.0 to 6.0, The response time of the electrode is few seconds and potentials generated are reproducible. The selectivity of the electrode over a large number of cations was studied. The values of selectivity coefficients are of the order 10^?2 for monovalent and 10^?3 for bivalent cations. Anions did not interfere. Potentiometric-titration of thallium nitrate with potassium chromate was also done using the membrane as an end point indicator electrode.     

Synthesen und Eigenschaften ethinylierter und trimethylsilylethinylierter Molekülsysteme mit 1,6-Methano[10]annulen-Partialstruktur

2-Trimethylsilylethinylated 1,6-methano[10]annulene1 a was obtained by reaction of 2-bromo-1,6-methano[10]annulene with trimethylsilylacetylene in the presence of bis-(triphenylphosphin-)-Pd (II) chloride and Cu(I) and also by reaction of 1,1-diiodo-2-(1,6-methano[10]annulene-2-yl)-ethene (2) withn-buthyl-lithium followed by hydrolysis.1 a reacts with 2N NaOH to 2-ethinyl-1,6-methano[10]annulene (1 b). 2,7- and 2,10-dibromo-1,6-methano[10]annulene can be substituted to give the trimethylsilylethinylated compounds3 a–6 a, which then can be transformed with 2N NaOH into the desilylated products3 b–5 b.

Wolfgang Kraus, Stuttgart-Hohenheim, mit den besten Wünschen in Freundschaft zum 60. Geburtstag gewidmet     

Trace,Alkaline and Alkaline-Earth Elements in Sea Water Samples from Terra Nova Bay - Ross Sea (ANTARCTICA): A Three-Year Period of Observation

Abstract

This report concerns the correlation of the analytical results relevant to some elements obtained in filtered sea water samples collected in Terra Nova Bay and the Ross Sea (Antarctica) during three Italian expeditions. The following ranges of variability of the medians of total concentrations (ng/l) - which include time effect among expeditions and bias effect among participant groups - were found for trace elements (single values refer to elements which were only determined once by one laboratory): Sb (260), As (1.2 10³), Cd (5–50), Cr (120), Co (4), Cu (110–230), Fe (435–445), Pb (6–52), Mn (15–88), Hg (3), Ni (185–580), Se (30) and Zn (242–265). Speciation studies pointed out that 10–40% of Cd, 15–60% of Cu and 20–50% of Pb were present in the samples as an ASV-labile fraction.

As for alkaline and alkaline-earth elements, the following concentration ranges in surface sea waters, expressed in mM, were found: Li ([1.4–3.0] 10^?2), Na (394–480), K(5.1–9.9), Ca (6.4–14.7), Mg (46.2–59.0) and Sr ([7.6–10] 10^?2).

Inter- and intra-laboratory data comparison, incorrect results, local variations of concentration, including pollution effects and pack melting effect, are discussed in detail.     

Lead-selective poly(vinyl choride) membrane electrodes based on heterocyclic thiocarboxylic acid

Heterocyclic thiocarboxylic acids have been designed to prepare polymeric membrane ion-selective electrode (ISE) for Pb²⁺. Construction, response characteristic and application of the lead ISEs are investigated. Better results have been obtained with membranes containing ligands L1∼L3 with bis(2-ethylhexyl) sebacate (DOS) as a plasticizer. Ionophores L1∼L3 are [(4,6-dimethyl-2-pyrimidinyl) thio] acetic acid (L1), (1,3,4-thiadiazole-2,5-diyldithio) diacetic acid (L2) and (1,3,4-thiadiazole-2,5-diyldithio) dipropionic acid (L3). The optimum electrodes have the composition of L1 (1.6): PVC (32.7): DOS (65.3): KT _p ClPB (0.4) (w/w), L2 (1.0): PVC (32.8): DOS (66.0): KT _p ClPB (0.2) (w/w), and L3 (1.0): PVC (32.7): DOS (65.4): KT _p ClPB (0.9) (w/w). The optimized membrane electrodes work well over a wide range of concentrations (1.0 × 10⁻⁵ ∼1.0 × 10⁻² M, 1.0 × 10⁻⁶ ∼1.0 × 10⁻² M, and 1.0 × 10⁻⁶ ∼1.0 × 10⁻² M) with the response slope of 27.4, 30.1 and 29.2 mV/decade, respectively. Potentiometric selectivities of the ISEs based on L1 ∼ L3 for Pb²⁺ over other interfering ions are determined with the fix interference method. The electrodes display good selectivity over a number of alkali, alkaline earth, transition and heavy metal ions. The lifetime of the electrodes is about 2 months and their response time is 20 s. Applications of these electrodes for the determination of lead in real samples and as indicator electrodes for potentiometric titration of Na₂SO₄ using Pb²⁺ solution are reported.     

Selection of A Suitable Solvent System for the Separation and Quantitation of Histamine

Abstract

The suitability of 79:21, 85:15 and, 90:10 of phosphate buffer: 50% methanol, as mobile phases, to separate and quantitate histamine in small plasma volume (<300 μl) was investigated by using a Dionex BioLC System coupled to a pulsed amperometric detector. Also, special attempts were made to reduce the time of analysis of each sample. Methylhistamine was used as an internal standard. the best results were obtained with the 79:21 mobile phase with concommittant reduction in analysis time from the current 1 sample per 90 min to 5 samples per 60 min suggesting that the method is suitable and cost effective.     

Metformin and Moroxidine Determination With Cu (II)

Abstract

Conductometric titrations of metformin and moroxidine are reported. The procedure is based on the copper-biguanide reaction which gives a pink soluble complex. Studies at several pH values and presence of NH₃ are carried out. NaOH-NH₃ (1:15) are added to 5 ml of biguanide aqueous solution and diluted to 60 ml and titrated with copper sulphate. Concentrations of metformin in 205x10^?4-1,7x10^?3 M range are determined. Foreign species presence is studied too.