A new 2-carboxylate-substituted 4,4 '-bipyridine ligand: coordination chemistry of 4,4 '-bipyridine-2-carboxylic acid and its synthetic intermediate 2-methyl-4,4 '-bipyridine

The first monocarboxylate- substituted 4,4'- bipyridine ligand, 4,4'- bipyridine- 2- carboxylic acid ( 4-( pyridin- 4- yl) pyridine- 2- carboxylic acid ( PPCAH)), has been successfully synthesized from 4,4'- bipyridine. Reactions with transition metals zinc and manganese were used to establish the coordination characteristics of the product, 4,4 '- bipyridine- 2- carboxylic acid, and of the synthetic intermediate, 2- methyl- 4,4'- bipyridine, by single- crystal X- ray diffraction. The ligand PPCAH is useful for the formation of metal- containing building blocks that can be used in the assembly of mixed- metal framework materials. The synthesis and structure of one such mixed- metal coordination polymer, Cu( PPCA)(2)HgI2, is also presented.