A three-dimensional CdII coordination polymer constructed from 1,1′-biphenyl-2,2′,5,5′-tetracarboxylate and 1,4-bis(1H-imidazol-1-yl)benzene ligands

The title coordination polymer, poly[[aqua(mu(5)-1,1'-biphenyl-2,2',5,5'-tetracarboxylato)bis[mu(2)-1,4-bis(1H-imidazol-1-yl)benzene]dicadmium(II)] dihydrate], {[Cd-2(C16H6O8)(C12H10N4)(2)(H2O)]center dot 2H(2)O}(n), was crystallized from a mixture of 1,1'-biphenyl-2,2',5,5'-tetracarboxylic acid (H(4)bpta), 1,4-bis(1H-imidazol-1-yl)-benzene (1,4-bib) and cadmium nitrate in water-dimethylformamide. The crystal structure consists of two crystallographically independent Cd-II cations, with one of the Cd-II cations possessing a slightly distorted pentagonal bipyramidal geometry. The second Cd-II centre is coordinated by carboxylate O atoms and imidazole N atoms from two separate 1,4-bib ligands, displaying a distorted octahedral CdN2O4 geometry. The completely deprotonated bpta(4-) ligand, exhibiting a new coordination mode, bridges five Cd-II cations to form one-dimensional chains via mu(3)-eta(1): eta(2):eta(1):eta(2) and mu(2)-eta(1):eta(1):eta(0):eta(0) modes, and these are further linked by 1,4-bib ligands to form a three-dimensional framework with a (4(2).6(4))(4.6(2))(4(3).6(5).7(2)) topology. The structure of the coordination polymer is reinforced by intermolecular hydrogen bonding between carboxylate O atoms, aqua ligands and crystallization water molecules. The solid-state photoluminescence properties were investigated and the complex might be a candidate for a thermally stable and solvent-resistant blue fluorescent material.