Chlorophyll Catabolites in Fall Leaves of the Wych Elm Tree Present a Novel Glycosylation Motif

Fall leaves of the common wych elm tree (Ulmus glabra) were studied with respect to chlorophyll catabolites. Over a dozen colorless, non‐fluorescent chlorophyll catabolites (NCCs) and several yellow chlorophyll catabolites (YCCs) were identified tentatively. Three NCC fractions were isolated and their structures were characterized by spectroscopic means. Two of these, Ug‐NCC‐27 and Ug‐NCC‐43, carried a glucopyranosyl appendage. Ug‐NCC‐53, the least polar of these NCCs, was identified as the formal product of an intramolecular esterification of the propionate and primary glucopyranosyl hydroxyl groups of Ug‐NCC‐43. Thus, the glucopyranose moiety and three of the pyrrole units of Ug‐NCC‐53 span a 20‐membered ring, installing a bicyclo[17.3.1]glycoside moiety. This structural motif is unprecedented in heterocyclic natural products, according to a thorough literature search. The remarkable, three‐dimensional bicyclo[17.3.1]glycoside architecture reduces the flexibility of the linear tetrapyrrole. This feature of Ug‐NCC‐53 is intriguing, considering the diverse biological effects of known bicyclo[n.3.1]glycosidic natural products.     

Magnetische Eigenschaften von η-Oxiden und η-Oxidhydriden der Dreistoffsysteme Ti-Co-O und Ti-Cu-O

Magnetic susceptibility measurements were performed on η-oxides of the systems Ti?Co?O and Ti?Cu?O, and the corresponding hydrides. In agreement with earlier investigations, it was found that the magnetic properties are strongly influenced by the amount of interstitial oxygen and hydrogen, respectively.     

Wasserstoffaufnahme und magnetisches Verhalten der intermetallischen Phasen Ti2(Ni,Co) und Ti2(Ni,Fe)

Hydrogen absorption by the intermetallic compounds Ti₂(Ni,Co) and Ti₂(Ni,Fe) with Ti₂Ni-structure (O _h ⁷ -Fd3m) is accompanied by an increase of the volume of the unit cell without any structural change, while the maximum value of absorbed hydrogen is practically independent of the alloy composition. By taking up hydrogen, the intermetallic compounds, showingPauli spin paramagnetism with complex temperature dependence, become either temperature independent paramagnetic [hydrides of Ti₂(Ni,Co)] or strongly temperature dependent paramagnetic, following a modifiedCurie-Weiss-Law [hydrides of Ti₂(Ni,Fe)], respectively.

Herrn Prof. Dr.H. Bittner zum 60. Geburtstag gewidmet.     

Die Kleinplattenmethode in der Dünnschichtchromatographie

Zusammenfassung In Fortsetzung unserer Arbeiten über Dünnschichtchromatographie der Zucker auf Mischschichten wurde die Abhängigkeit der Steighöhe von der Zeit untersucht. Es ergab sich, daß eine minimale Laufhöhe von 6 cm bei einer Laufzeit von 6 bis 10 Minuten genügt, um noch brauchbare Trennungen zu erzielen. Eine Kleinplattenmethode für minimalste Substanzmengen wurde entwickelt. Diese Methodik ist gut geeignet zur Überprüfung von Reaktionen mit kleinsten Mengen und zur Untersuchung von Säften lebender Pflanzen.

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Summary In continuation of the authors studies of thin layer chromatography of sugar on mixed layers, a study was made of the relation between the height of ascent and time. It was found that a minimal ascent of 6 cm with a running time of 6 to 10 minutes is sufficient to obtain separations that are still usable. A small plate method was devised for the minimum amounts and for the investigation of the juices of living plants.

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Résumé A la suite de nos travaux sur la Chromatographie en couche mince des sucres en mélanges, nous avons étudié la dépendance du déplacement par rapport au temps. Nous avons trouvé qu'un déplacement minimal de 6 cm dans un temps de 6 à 10 minutes suffisait pour obtenir des séparations encore utilisables. Nous avons mis au point une méthode sur de petites surfaces pour des quantités de substance extrêmement faibles. Cette méthode convient pour le contrôle des réactions s'effectuant sur de très faibles quantités et pour l'étude des sucs des plantes vivantes.