The synthesis of novel norbornene based polyzwitterions via ring opening metathesis polymerization (ROMP) is present. Trifluoracetic acid (TFA) was used as a solvent to provide a homogenous medium for the polymerization reaction of sulfobetaines with the commercially available Hoveyda-Grubbs’ initiator. In order to prevent the competitive complexation via carboxylate functional group of the ruthenium metal center, we carried out the controlled polymerization of ethyl protected carboxybetaines monomers.

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Two isomeric pyridine-substituted norbornenedicarboximide derivatives, namely N-(pyridin-2-yl)-exo-norbornene-5,6-dicarboximide, (I), and N-(pyridin-3-yl)-exo-norbornene-5,6-dicarboximide, (II), both C(14)H(12)N(2)O(4), have been crystallized and their structures unequivocally determined by single-crystal X-ray diffraction. The molecules consist of norbornene moieties fused to a dicarboximide ring substituted at the N atom by either pyridin-2-yl or pyridin-3-yl in an anti configuration with respect to the double bond, thus affording exo isomers. In both compounds, the asymmetric unit consists of two independent molecules (Z' = 2). In compound (I), the pyridine rings of the two independent molecules adopt different conformations, i.e. syn and anti, with respect to the methylene bridge. The intermolecular contacts of (I) are dominated by C-H...O interactions. In contrast, in compound (II), the pyridine rings of both molecules have an anti conformation and the two independent molecules are linked by carbonyl-carbonyl interactions, as well as by C-H...O and C-H...N contacts.

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