Three PbII coordination polymers based on 2-(pyridin-2-yl)-1H-imidazole-4,5-dicarboxylic acid: Syntheses, crystal structures, and fluorescent properties

Zwitterionic 4-carboxy-2-(pyridinium-2-yl)-1H-imidazole-5-carboxylate

The title compound, C10H7N3O4, is zwitterionic, with one carboxyl group deprotonated and the pyridyl group protonated. The pyridine ring is close to coplanar with the imidazole ring, making a dihedral angle of 2.79 (8)°, this conformation being maintained by the presence of an intramolecular O—H...O hydrogen bond. In the crystal, two sets of N—H...O hydrogen bonds link the molecules through three conjoined cyclic hydrogen-bonding interactions, with two R 1 2(7) and one R 2 2(10) motifs, forming centrosymmetric cyclic dimers. These are linked through C—H...O hydrogen bonds, giving a supramolecular chain structure extending along the b-axis direction.

Synthesis, characterization and properties of a family of lead(ii)–organic frameworks based on a multi-functional ligand 2-amino-4-sulfobenzoic acid exhibiting auxiliary ligand-dependent dehydration–rehydration behaviours

A simplified representation of the architectures and auxiliary ligand-dependent dehydration–rehydration behaviours of 1–4.