Synthesis and Encapsulation of Uniform Star-Shaped Block-Macromolecules.

Linear uniform oligomers synthesized via a two-step iterative cycle are postmodified with uniform octaethylene glycol monomethyl ether and finally coupled via azide-alkyne cycloaddition to yield uniform star-shaped block macromolecules with a mass ranging from 10 to 14 kDa. Each of the molecules is carefully characterized by NMR, electrospray ionization mass spectrometry (ESI-MS), and size exclusion chromatography (SEC) to underline their purity as well as their uniformity. The obtained star-shaped macromolecules are investigated in their ability to encapsulate dye molecules by carrying out qualitative solid-liquid phase transfer experiments.

Sequence-definition in stiff conjugated oligomers.

The concept of sequence-definition in the sense of polymer chemistry is introduced to conjugated, rod-like oligo(phenylene ethynylene)s via an iterative synthesis procedure. Specifically, monodisperse sequence-defined trimers and pentamers were prepared via iterative Sonogashira cross-coupling and deprotection. The reaction procedure was extended to tetra- and pentamers for the first time yielding a monodisperse pentamer with 18% and a sequence-defined pentamer with 3.2% overall yield. Furthermore, three novel trimers with a 9H-fluorene building block at predefined positions within the phenylene ethynylene chain were synthesised in 23-52% overall yields. Hence, it was confirmed that a functionality of interest can be incorporated selectively at a pre-defined position of these monodisperse oligomers. All respective intermediate structures were fully characterised by proton and carbon NMR, mass spectrometry, size-exclusion chromatography, and IR spectroscopy. Additionally, thermal and optical transitions are reported for the different oligomers.