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

Abstract

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)₂HgI₂, is also presented.