Supramolecular control of oligothienylenevinylene-fullerene interactions: evidence for a ground-state EDA complex

Complementary hydrogen-bonding interactions between a barbituric acid-substituted fullerene derivative (1) and corresponding receptor (2) bearing thienylenevinylene units are used to assemble a 1:1 supramolecular complex (K = 5500 M(-1)). Due to the close proximity of the redox-active moieties within the assembly, strong ground-state electron-donor-acceptor interactions are observed. Photoinduced electron transfer from electron-rich thienylenevinylene subunits to the fullerene is very fast (k(et) = 5.5 x 10(12) s(-1)), as determined by fs-time-resolved transient absorption spectroscopy. [reaction: see text]     

Liquid chromatography-mass spectrometry in metabolic research. I. Metabolites of benzbromarone in human plasma and urine.

Seven benzbromarone metabolites were identified in human plasma and urine by electron-impact mass spectrometry after semipreparative high-performance liquid chromatographic fractionation and/or by liquid chromatography-mass spectrometry using a thermospray interface. The major metabolite in plasma and urine was a hydroxybenzofuranoyl species; the 1-hydroxyethyl entity was identified as a minor metabolite. Five urinary metabolites occurred in trace amounts, all of them carrying OH and/or C = O groups in different positions. The hydroxybenzofuranoyl metabolite has often been mistaken for benzarone in previous studies.     

Ion-exchange resins containing s-bonded dithizone and dehydrodithizone as functional groups : Part 2. Desoprtion properties and development of separation procedures for gold and platinum group metals

The desorption of precious metals from the PD and PTD ion-exchange resins, containing S-bonded dithizone and dehydrodithizone as functional groups, is described. Each sorbent was loaded batchwise with individual or combined metals and then treated with excess of various extracting agents (6 M hydrochloric acid, 2 M perchloric acid, ammonium nitrate, sodium thiocyanate, thiourea). Strong retention of some adsorbed metals and instability during the loading and elution stages were found with the PD resin, but a selective separation of palladium and gold from accompanying metals was possible. The PTD resin had superior properties. Unsual effects were detected when elution rates were compared for individual metals and mixtures. While Pd and Pt, loaded individually, were desorbed quantitatively by thiourea, co-extracted Ir(IV) completely inhibited their elution. The regeneration of PTD by special sequences of eluents was utilized for selective chromatographic separation of Pd, Pt, Os, Au and (with restrictions) Ir from each other and also from large amounts of base metals and salts.     

Speciation of trace amounts of aluminium in percolating water of forest soil by online coupling HPLC-ICP-MS

Procedures were developed for the speciation of trace amounts of aluminium present in percolating water of forest soil by online coupling of different chromatographic separation methods to an ICP-MS detection system. Inorganic and organic aluminium species were fractionated on a cation exchange column IONPAC CG12 (10-32). Phytotoxic polymeric aluminium hydroxides, as e.g. Al₁₃ (AlO₄Al₁₂(OH)₂₄(H₂O)₁₂ ⁷⁺), were determined using pyrocatechol violet (PCV) as a species dependant complexing reagent prior to the cation exchange step. Size fractionation of the organic aluminium species was obtained by size exclusion chromatography using the columns Superdex-75-HR 10/30 and Superdex-Peptide-HR 10/30. Validation of the speciation procedures proved that online coupling HPLC to the element selective and sensitive ICP-MS detection system leads to low detection limits of 0.3–0.6 μg/L and high precision and reproducibility (1.2–3.5%) of the speciation procedures. Speciation data determined for aluminium in a percolating water of the Zierenberg catchment are given.     

Isolation of ent-labdane (+)-12,15-epoxylabda-8(17), 12,14-trien-16-yl acetate from the seeds of Turraeanthus africanus and its cytostatic/cytotoxic effect on the growth of cancer cells in vitro

(+)-12,15-Epoxylabda-8(17),12,14-trien-16-yl acetate has been isolated from the seed kernels of Turraeanthus africanus (Nelw. ex DC). The stereo structure was confirmed by 1D-and 2D-NMR spectroscopy. Cytostatic/cytotoxic test of (I) on the growth of cancer cells in vitro gave positive results. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 38–39, January–February, 2006.     

Formazane als funktionelle Gruppen chelatbildender Ionenaustauscher

Zusammenfassung Kovalent an Kieselgel gebundene Aminopropylgruppen (Si-NH₂) werden unter Alkylierung zum quaternären Ammoniumsalz (Si-Q) umgesetzt, aus dem durch Sorption von sulfonsäuresubstituierten Formazanen (Fm) chelatbildende Kieselgele (Si-QFm) erhalten werden. Die Ionenaustauscher (Si-QFm) werden hinsichtlich ihrer Stabilität, Sorption- und Desorptionseigenschaften unter statischen und dynamischen Bedingungen mit ähnlich modifizierten Polystyrolen verglichen. Es wurde beobachtet, daß die anorganische und organische Matrix das chelatbildende Verhalten der Liganden gegenüber Pt(IV), Pd(II) und Ag(I) unterschiedlich beeinflußt. Mit geringen Mengen an formazanbeladenem Kieselgel sind Anreicherungen und Trennungen von Silber bei Fließgeschwindigkeiten bis zu 7 ml/min möglich.

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Formazans as functional groups of chelating ion-exchangersIV. Properties of formazan loaded silica gel

Summary Quaternary ammonium groups, chemically bound to silica gel (Si-Q) were synthesized by quaternization of aminopropyl-functionalised silica (Si-NH₂). Si-Q was loaded with sulphonated formazans (Fm) to get the chelating supports Si-QFm. Stability, sorption- and desorption propperties of formazan modified silica were compared with similar modified polystyrene under static and dynamic conditions. It was observed that the chelating behaviour of the ligands in the presence of Pt(IV), Pd(II) and Ag(I) is affected by inorganic and organic matrix in a different way. Enrichment and separation of Ag(I) is possible by flow rates up to 7 ml/min with minimum amounts of chelating silica gel.

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Teil III: siehe [6]

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Dem Land Nordrhein-Westfalen sowie dem Fonds der Chemischen Industrie danken wir für die finanzielle Förderung dieser Untersuchung.