Structural aspects and electronic absorption of the hydroxyphenanthroperylene quinones fringelit D,hypericin, and stentorin

Summary PPP type semiempirical quantum chemical calculations of absorption spectra were performed for hypericin, fringelit D, stentorin, and their respective conformers, tautomers, and deprotonated species. The results agree with the experimental absorption spectra of hypericin, stentorin, and fringelit D, their deprotonated species, and the polarized absorption spectra of an ,-long chain appended hypericin derivative embedded in stretched polyethylene.

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Strukturelle Aspekte und elektronische Absorptionseigenschaften der Hydroxyphenanthroperylenchinone Fringelit D, Hypericin und Stentorin

Zusammenfassung Semiempirische quantenchemische Rechnungen (PPP-Typ) der Absorptions-spektren von Hypericin, Fringelit D, Stentorin und ihrer Konformeren, Tautomeren und deren Deprotonierungsprodukten wurden durchgeführt. Die Resultate stehen in Einklang mit den experimentellen Absorptionsspektren von Hypericin, Fringelit D, Stentorin, ihrer Deprotonierungsprodukte und dem polarisierten Absorptionsspektrum eines in gestrecktem Polyethylen eingebetteten ,-substituierten Hypericinderivates.

     

Beiträge zur Chemie der Pyrrolpigmente, 70. Mitt.: Zum aktiven Transport mit tripyrrinoiden Liganden

The tripyrrin carboxylic acid6 exhibits a pronounced efficiency for carrier mediated proton driven secondary active transport (counter transport) for a series of toxic or valuable cations in a bulk chloroform membrane. In case of Zn⁺⁺ ions the mechanism including complete concentration profiles forNerst diffusion layers and bulk phase have been established. This compound might be used for detoxification or enrichment of precious metals using membrane separation systems.

Herrn Prof. Dr.A. Neckel mit den besten Wünschen zum 60. Geburtstag gewidmet.     

Ferrocenasymmetrie, 5. Mitt.: Die Anwendung eines halbempirischen Rechenverfahrens auf optisch aktive Ferrocenderivate

The procedure ofBrewster was employed in the calculation of the molecular rotation of optically active derivatives of 1,2-tetramethylene-ferrocene, which (in addition to ferrocene asymmetry) contain asymmetric (chiral) centers in the cyclohexene part of the molecule. Satisfactory agreement between the calculated and observed values for the rotations was obtained throughout. In one case, the calculation of the absolute configuration of the planarasymmetric part was successful; it was found to be in agreement with the results of an independent (experimental) method employed earlier. The absolute conformation of some of the ferrocene derivatives is discussed with the aid of optical circular dichroism.     

Zur Chemie der Pyrrolpigmente, 56. Mitt.

From an investigation of the ICD of bilatrienes-abc and 2,3-dihydrobilatrienes-abc induced by mixtures of CCl₄ with (+)-cis-Pinane, (–)-lactic and (+)-tartaric acid esters it is concluded that specific interactions between chromophore and the chiral reagents afford a partial resolution of the labile racemate of helices. Attaching chiral residues covalently to the chromophore induces very low resolution of the same kind in case of apolar ligands like a cholesteryl-residue. However, with polar ligands as in the case ofBoc-lysyl derivatives enantiomeric excesses up to 90% are achieved depending on the solvent used.

Herrn Prof. Dr.Karl Schlögl zu seinem 60. Geburtstag gewidmet.     

Beiträge zur Chemie der Pyrrolpigmente, 9. Mitt.: Bildung,Struktur und Konfiguration vonZ- undE-Arylmethyliden-3,4-dimethyl-3-pyrrolin-2-onen

The condensation of 3.4-dimethyl-3-pyrrolin-2-one with p-methyl-, p-chloro-benzaldehyde and ferrocenealdehyde yields theZ-andE-isomers of the corresponding condensates. Due to kinetic control theZ-isomers are obtained almost exclusively in this reaction. TheE-isomers of the two firstmentioned products can be produced by photochemical isomerization. The structures (tautomeric forms) and configurations of the isomers were established by the Lanthanide-induced-shift-technique and by evaluating the Nuclear-Overhauser-Effect.     

Concerning the acidity and hydrogen bonding of hydroxyphenanthroperylene quinones like fringelite D,hypericin, and stentorin

Summary The strongly enhanced acidity of the bay hydroxyl group as compared to the respectiveperi hydroxyl groups of fringelite D, hypericin, and stentorin could be rationalized on the basis of a vinylogous carboxylic acid and was nicely corroborated by semiempirical calculations of the AM1 type. Experimental data obtained from several independent experimental methods, like polarized absorption spectroscopy, hole burning, and isotope effects, as well as from semiempirical AM1 and 6–31G levelab initio calculations conclusively pointed to dissymmetrical hydrogen bonding systems in both theperi andbay regions of the correspondingbay phenolate ions.

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Zu Acidität und Wasserstoffbrückenbindung von Hydroxyphenanthroperylenchinonen wie Fringelit D, Hypericin und Stentorin

Zusammenfassung Die stark erhöhte Acidität der bay-Hydroxylgruppen gegenüber jener derperi-Hydroxylgruppen von Fringelit D, Hypericin und Stentorin läßt sich auf der Basis einer vinylogen Carbonsäure verstehen und wurde auch durch semiempirische Rechnungen vom AM1-Typ erhärtet. Daten aus unabhängigen Experimenten wie Polarisationsspektroskopie, Lochbrennen und Isotopeneffekte sowie semiempirische AM1- undab initio-Rechnungen auf 6–31G Niveau belegen ein unsymmetrisches Wasserstoffbrückenbindungssystem sowohl für denperi-als auch denbay-Bereich der entsprechendenbay-Phenolationen.

     

UV-VIS and CD-spectroscopic investigations of intermolecular interactions of bile pigments with small proteins

Summary The intermolecular complex formation of bilirubin and biliverdin with two proteins (basic pancreatic trypsin inhibitor and lysozyme) were studied by optical and chiroptical methods. Evidence for specific intermolecular interactions of biliverdin with both proteins was found. Bilirubin forms a soluble complex only with lysozyme.

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UV-VIS und CD-spektroskopische Untersuchungen intermolekularer Wechselwirkungen von Gallenpigmenten mit kleinen Proteinen

Zusammenfassung Die intermolekulare Komplexbildung von Bilirubin und Biliverdin mit zwei Proteinen (basischer pankreatischer Trypsininhibitor und Lysozym) wurden mittels optischer und chiroptischer Spektroskopie untersucht. Für Biliverdin konnten intermolekulare Wechselwirkungen mit beiden Proteinen nachgewiesen werden. Bilirubin bildet nur mit Lysozym einen löslichen Komplex.