Über die indigoähnlichen Gruppen von blauen Farbstoffen aus Isatin

Liquid crystallinity and supramolecular organization of regioisomeric isatin derivatives: an experimental and theoretical study

Spatially organized chromophores can be beneficial for advanced applications like for example, organic solar cells, laser technology or non-linear optic devices as well as supramolecular photochemistry. Of particular interest are non-static ordered forms of molecular organization as for example, liquid crystals. With this in mind we synthesised four new regioisomeric isatin derivatives by Suzuki-Miyaura coupling of 4-dodecyloxyphenylboronic acid with all four possible regioisomers of bromoisatin. Liquid crystalline properties are found for 5-(4-dodecyloxyphenyl)isatin, while the other regioisomers do not display a mesomorphic behaviour. The synthesis, physicochemical investigations including polarization microscopy, differential scanning calorimetry and X-ray investigations are discussed and accompanied with density functional theory calculations with respect to the target molecules and their possible H-bonded aggregates. Two distinct setups of supramolecular assemblies for such isatin derivatives are discussed and a model for the mesophase is proposed.

[Metabolic products of microorganisms. 156. Synthesis and biosynthesis of substituted tryptanthrins (author's transl)]

Candida lipolytica synthesizes the antibiotic tryptanthrin from 1 mole tryptophan and 1 mole anthranilic acid. When feeding tryptophan and substituted anthranilic acids, or substituted tryptophans and anthranilic acid, we could isolate and identify the expected derivatives of tryptanthrin. The enzymes of the biosynthesis of tryptanthrin, with the exception of bromotryptophan, had no specifity for these substrates. In addition to these experiments substituted tryptanthrines were chemically synthesized. We checked them for antibiotic action; the halogen compounds turned out to be especially effective.