Pyridine anionic polymer coordinating

Several recent reviews have projected about the gigantic rise in the number of publications about coordination polymers per year since 1990. In the majority of coordination polymers, either the O-atoms of anions (carboxylates, nitrates, sulfates, phosphates, phenolates) and/or the N-atoms of cyanates, cyanides, amines, pyridines engage in coordination bonds with transition-metal atoms (Tr and Tr-N)- A Cambridge structural database (CSD) search indicates that the coordination polymers propagated by Tr O (7074 hits) are the major portion compared to those of Tr-N (6392 hits). In about 53% of the Tr-O type, the O-atom belongs to carboxylates, whereas in about 40% of the Tr-N kind, the N-atom belongs to pyridine.These statistics indicate the importance of carboxylate and pyridine moieties in generating coordination polymers. 

The first use of chiral helical polymers bearing no chiral side chains for chiral reaction induction was realized by Reggelin et at. in 2002 [69]. Two poly(methyl methacrylate)-based chiral polymers (40) was prepared by hehx-sense selective anionic polymerization of sterically congested methacrylates with a chiral base mixture as initiator. The pyridine moieties in helical polymers allowed various metal coordinations [70] or formation of ionic pairs [71]. Their complexes with palladium precursor were found to be active catalysts for the allyHc substitution reaction of l,3-diphenylprop-2-enyl acetate (Figure 4.36). Although the ee values were only moderate (<33%), this research opened up a new area for asymmetric catalysis with unnatural helical chiral polymers. 

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