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Synthesis of a poly(2-azanorbornene) with a high degree of cis-TT-stereoregularity and a regular secondary solution structure†
Elisabeth Rossegger,László Oláh,Roland Fischer,Petra Kaschnitz,Olívia Varga,Mihály Kállay,Gregor Scheipl,Franz Stelzer,Frank Wiesbrock
Polymer Chemistry Pub Date : 07/17/2012 00:00:00 , DOI:10.1039/C2PY20219K
Abstract

Methyl-N-(1-phenylethyl)-2-azabicyclo[2.2.1]hept-5-ene-3-carboxylate (AzaN) was synthesized as a diastereomerically pure monomer and subsequently polymerized with the ruthenium-based M31® catalyst. The poly(2-azanorbornene)s with polymerization degrees in the range from 100 to 300 exhibited high degrees of cis-TT stereoregularity in contrast to previously reported poly(2-azanorbornene)s that were prepared with molybdenum-based catalysts and exhibited cis-HT and trans-HT stereoregularity. The formation of regular secondary structures in acetonitrile solution was verified by circular dichroism and AFM measurements and supported by theoretical calculations of a polymer model with eight repeating units. Of special note are the large diameters of the secondary structures that are indicative of a multiple-strand filament.

Graphical abstract: Synthesis of a poly(2-azanorbornene) with a high degree of cis-TT-stereoregularity and a regular secondary solution structure
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