A new structural family of gas-sorbing coordination polymers derived from phenolic carboxylic acids

The structure of Li(inox)center dot 2/3DMF (inox(-) = the N-oxide of the isonicotinate anion) consists of a 3D framework with solvent-filled, square cross-section channels of approximate dimensions 5.5 x 5.5 angstrom. Unfortunately, the Li(inox) framework is unstable upon removal of DMF from the channels. When the structurally related 4-hydroxybenzoic acid (H(2)hba) was used in place of Hinox, and Zn2+ in place of the Li+, a structurally similar but more robust network, Zn(hba), was obtained; the isostructural compound, Co(hba), may also be prepared. Longer ligands with phenolate and carboxylate functional groups at opposite ends, such as the dianions of 4-coumaric acid (H(2)cma) and 4'-hydroxy-4-biphenylcarboxylic acid (H(2)hbpc), in combination with Zn2+ yield Zn(cma) and Zn(hbpc) frameworks, respectively, with the same PtS topology but with larger channels. The coordination polymers remain intact after desolvation and exhibit microporosity, showing the ability to sorb significant quantities of CO2, CH4, and H-2.