Bipyridne Building Blocks for Self-Organization Systems: First Complete NMR-spectroscopic Investigation of 6,6'-Disubstituted 2,2'-Bipyridines Obtained via N-Oxidation Route and Related Reactions

One-and two-dimensional NMR-spectroscopic data of eight 6,6'disubstituted 2,2'-bipyridines, prepared by the N-oxidation route, were used to confirm their structures.These key compounds in supramolecular construction lead to the characterization of larger oligo(bipyridine) building blocks.Furthermore some related reactions are described which lead to unsymmetrically functionalized bipyridines or can be used for the purification of bishydroxy compounds.The design of organic or inorganic molecular compounds with the ability to form well-defined supramolecular architectures is one major goal in modem synthetic chemistry.'Such systems often show recognition-directed, self-assembly feature^.'.^One of the most famous self-organization systems is the oligo(bipyridine) metal complexes68 which spontaneously form helical architectures in the presence of A ~' or CU' cations, whereby two oligo(bipyridine) strands wrap around the metal cations to form structures, similar to the Watson and Crick double-helix in nucleic acids?Our research interest is to build these special building blocks into synthetic macromolecules or dendrimers in order to obtain new ordered systems with specific structural and functional properties.'0.'3We recently published optimized routes to functionalized 6,6'-disubstituted 2,2'-bipyridines in a multigram scale using N-oxidation procedures to hydroxymethyl terminated hipyridinesI4 and a general new synthetic approach towards unsymmetrically functionalized bipyridine and oligo(bipyridine) building