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NMR Study of Hyperbranched Polyphenylenes from the AB2, (AB2 + AB) and (A2 + B3) Methods

✍ Scribed by Hartmut Komber; Katrin Stumpe; Brigitte Voit

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
263 KB
Volume
207
Category
Article
ISSN
1022-1352

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✦ Synopsis

Abstract

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~).

magnified imageSelected 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~).

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