ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Pyrrolpigmente, 79. Mitt. Zum strukturellen Einfluß stark raumerfüllender Reste bei 10-substituierten 1,19-Bilindionen (1989)
    Springer
    Monatshefte für Chemie 120 (1989), S. 35-43 
    Details
    ISSN: 1434-4475
    Keywords: 10-Substituted 1,19-bilindiones ; Conformational analysis ; 13C-NMR ; 1H-NMR ; Absorption spectroscopy ; Semiempirical calculations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1,19-Bilindiones bearing a phenanthryl, mesityl,tert-butyl, and isopropyl substituent at the C-10 position were synthesized. Conformational analysis using13C- and1H-NMR spectroscopic techniques and absorption spectroscopy together with semiempirical calculations revealed that the aryl derivatives adopt the common circular helical geometry, whereas thetert-butyl derivative is heavily distorted. The mean planes of the two dipyrrinone moieties are orthogonally positioned to each other. The 10-isopropyl-bilindione tautomerizes to the 10-isopropyliden-biladiene-ac.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00809647
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    On the bromination of hypericin: The gymnochrome chromophores (1993)
    Springer
    Monatshefte für Chemie 124 (1993), S. 77-81 
    Details
    ISSN: 1434-4475
    Keywords: Bromo-hypericines ; Gymnochromes ; 1H-NMR ; 13C-NMR ; UV-Vis ; pK a values ; Fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Schrittweise elektrophile Bromierung von Hypericin in Pyridin als Lösungsmittel liefert regioselektiv 2,5-Dibromhypericin, 2,5,9-Tribromhypericin und 2,5,9,12-Tetrabromhypericin. Diese Verbindungen wurden durch NMR-, UV-Vis- und Fluoreszenz-Spektrometrie sowie durchpK a - undpk* a -Messungen charakterisiert. Diese Eigenschaften wurden mit jenen des Hypericins und der kürzlich isolierten Gymnochrome verglichen.
    Notes: Summary Stepwise electrophilic bromination of hypericin in pyridine as the solvent yields regioselectively 2,5-dibromohypericin, 2,5,9-tribromohypericin, and 2,5,9,12-tetrabromohypericin. The compounds were characterized by means of NMR-, UV-Vis-, and fluorescence-spectra, andpK a andpK* a measurements. These properties were compared with those of hypericin on the one hand and of the recently isolated gymnochromes on the other hand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00808512
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Beiträge zur Chemie der Pyrrolpigmente, LVIII Phytochrommodellstudien: Konformationsanalytische Untersuchungen an 2,3-Dihydrobilatrien-abc-Derivaten (1984)
    Springer
    Monatshefte für Chemie 115 (1984), S. 1443-1451 
    Details
    ISSN: 1434-4475
    Keywords: 1H-NMR ; NOE ; Lanthanide induced shifts ; 3,4-Dihydropyrrome-thenones ; 2,3-Dihydrobilatriene-lactim ethers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Two 3,4-dihydropyrromethenones and two 2,3-dihydrobilatrienes-abc O-methylated at rings A and D resp. have been prepared. Their configurations were established as (Z), (E), (Z, Z, Z) and (Z, Z, Z), respectively, using1H-NMR-techniques (NOE); they are also shown to exist predominantly in the lactam form. Within the pyrromethene fragment of the bilatrienes the pyrrolic and pyrroleninic ring type depends on the position of O-methylation. A helical all-synperiplanar conformation in solution could be established for all cases by applying the lanthanide induced shift (LIS) technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00816343
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    On the nature of “soluble” hypericin inHypericum species (1992)
    Springer
    Monatshefte für Chemie 123 (1992), S. 731-739 
    Details
    ISSN: 1434-4475
    Keywords: “Soluble” Hypericin ; Hypericin-, Pseudohypericin-, Protohypericin-, Protopseudohypericin-, Potassium salts ; 1H-NMR ; 13C-NMR ; Droplet counter-current chromatography ; Hypericum perforatum L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die zwei roten und zwei violetten „löslichen“ Pigmente ausHypericum Arten wurde durch Extraktion, Chromatographie und Tropfen-Gegenstromchromatographie isoliert. Im Gegensatz zu authentischem Hypericin sind diese in organischen Lösungsmitteln und sogar in Wasser löslich. Aus NMR-Experimenten wurde abgeleitet, daß Hypericin, Pseudohypericin, Protohypericin und Protopseudohypericin in diesen Pflanzen als deren rasch interkonvertierende 3- und 4-Phenolationen vorliegen. Durch AAS wurde gefunden, daß diese Phenolationen Kalium als Gegenion aufweisen. Das Kalium- und N-Ethyl-N,N-diisopropylammonium-Salz des Hypericins wurden zu Vergleichszwecken dargestellt. Ein präparatives Verfahren zur Isolierung von Hypericin und Pseudohypericin aus Pflanzenmaterial wurde entwickelt.
    Notes: Summary The two red and two violet “soluble” pigments ofHypericum species were isolated by means of extraction, chromatography, and counter-current droplet chromatography. In contrast to authentic hypericin, they are soluble in common organic solvents and even in water. Using NMR experiments it was deduced that hypericin, pseudohypericin, protohypericin, and protopseudohypericin are present in the plant as their rapidly interconverting 3- and 4-phenolate ions. From AAS the main counter-ion of these phenolates was derived to be potassium. The potassium and N-ethyl-N,N-diisopropylammonium salts of hypericin were synthesizcd for comparison. A preparative procedure to isolate hypericin and pseudohypericin from plant material was developed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00812322
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...