Journal
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume 125, Issue 43, Pages 13284-13297Publisher
AMER CHEMICAL SOC
DOI: 10.1021/ja035127d
Keywords
-
Categories
Ask authors/readers for more resources
Advanced solid-state NMR methods under fast magic-angle spinning (MAS) are used to study the structure and dynamics of large supramolecular systems, which consist of a polymer backbone with dendritic side groups and self-assemble into a columnar structure. The NMR experiments are performed on as-synthesized samples, i.e., no isotopic enrichment is required. The analysis of H-1 NMR chemical-shift effects as well as dipolar H-1-H-1 or H-1-C-13 couplings provide site-specific insight into the local structure and the segmental dynamics, in particular, of phenyl rings and -CH2O- linking units within the dendrons. Relative changes of H-1 chemical shifts (of up to -3 ppm) serve as distance constraints and allow protons to be positioned relative to aromatic rings. Together with dipolar spinning sideband patterns, pi-pi packing phenomena and local order parameters (showing variations between 30% and 100%) are selectively and precisely determined, enabling the identification of the dendron cores as the structure-directing moieties within the supramolecular architecture. The study is carried out over a representative selection of systems which reflect characteristic differences, such as different polymer backbones, sizes of dendritic side groups, or length and flexibility of linking units. While the polymer backbone is found to have virtually no effect on the overall structure and properties, the systems are sensitively affected by changing the generation or the linkage of the dendrons. The results help to understand the self-assembly process of dendritic moieties and aid the chemical design of self-organizing molecular structures.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available