Beiträge zur Chemie der Pyrrolpigmente, 1. Mitt.: Der induzierte Circulardichroismus einiger Pyrromethenderivate in cholesterischer Mesophase (original) (raw)

Beiträge zur Chemie der Pyrrolpigmente, 47. Mitt

Monatshefte für Chemie / Chemical Monthly, 1983

Carrier mediated transport of bilirubin, biliverdin, their dimethylesters and aetiobiliverdin-IV-γ is measured using a variety of potential carriers like proteins, peptides, tensides and β-cyclodextrin in a bulk membrane model. A strong dependence of the transport flux densities on structural details of the carriers as well as of the bile pigments themselves is observed.

Beiträge zur Chemie der Pyrrolpigmente, 65. Mitt

Monatshefte für Chemie - Chemical Monthly, 1986

The title compound 1 is found to be protonated corresponding to pKa's of 2.5 and 0.5, thereby being two orders of magnitude less basic than bilatrienes-abc. Its d e p r o t o n a t i o n (p K a = 17.1) is found to be less easy than in case of the bilatrienes. 1 is shown to exhibit a very pronounced reactivity for nucleophiles at the methine positions "10" and" l 5"-a thiole adduct and the 10,15-dihydroderivative of 1 are isolated and characterised. In contrast to the bilatrienes the adduct formation is irreversible. Accordingly, no diastereomers at exocyclic double bonds could be produced photochemically. Complexation of the lactam oxygens is achieved in case of Lewis acids (eg. A1C13), chelation after addition of a proton acceptor is observed in a few cases only (Zn ++, Hg ++, In+++).

Beiträge zur Chemie der Pyrrolpigmente, 49. Mitt

Monatshefte Fur Chemie, 1983

From kinetic and equilibrium measurements the activation and thermodynamic parameters of diastereomeric 2,3-dihydrobilatrienes-abc in positions “4” and “15” are deduced. Compared to bilatrienes-abc a pronounced thermal lability of these diastereomers is observed—the exocyclic double bond of the saturated lactam ring being the more labile one. This feature may be of relevance to the thermal cascades and dark reactions observed for

Beiträge zur Chemie der Pyrrolpigmente, 6. Mitt.: Dipolmomente von substituierten Pyrromethenen

Monatshefte Fur Chemie, 1974

The dipole moments of three symmetrically and one, unsymmetrically substituted pyrromethene derivatives were determined using cyclohexane as solvent. By comparison of these moments with those obtained from a semiempirical quantum mechanical treatment including all valence electrons (CNDO/2), the predominance of one tautomeric form of the unsymmetrically substituted species was deduced.