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NMR Study of Hyperbranched Polyphenylenes from the AB 2 , (AB 2 + AB) and (A 2 + B 3 ) Methods
Author(s) -
Komber Hartmut,
Stumpe Katrin,
Voit Brigitte
Publication year - 2006
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200600351
Subject(s) - steric effects , nmr spectra database , monomer , solvent , chemistry , spectral line , polymer , carbon 13 nmr , proton nmr , polymer chemistry , two dimensional nuclear magnetic resonance spectroscopy , materials science , stereochemistry , organic chemistry , physics , astronomy
Summary: The 1 H NMR and 13 C NMR spectra of hyperbranched polyphenylenes synthesised from AB 2 , (AB 2 + AB) and (A 2 + B 3 ) monomers (A: ethynyl group; B: cyclopentadienonyl group) were analysed with respect to the characteristic substructures of these polymers. The broad and overlapping NMR spectra were studied by a combination of 1D and 2D NMR techniques. Furthermore, appropriate model compounds were synthesised, and their 1 H and 13 C NMR spectra were fully assigned. The signal assignments achieved allow to substantiate the different hyperbranched polyphenylene structures. Steric hindrance in densely packed di‐ and trihexaarylphenyl substituted units of the (A 2 + B 3 ) polyphenylenes results in the decrease of the rotation frequency of phenyl rings in these structures to such an extent that the motion is slow on the 1 H NMR time scale. This can be proved both by EXSY and variable‐temperature experiments. Steric constraints were also deduced for the AB 2 polyphenylenes from signal line shape.Selected spectra from a VT 1 H NMR experiment on polymer 7b (solvent: C 2 D 2 Cl 4 ; *– 13 C satellites of the solvent; signal at 7.3 ppm due to traces of CHCl 3 ).