Three New MOFs Induced by Organic Linker Coordination Modes: Gas Sorption, Luminescence, and Magnetic Properties

By using a new 4,6-bis(imidazol-1-yl) isophthalic acid ligand (H₂ bimip) with imidazolyl and carboxyl bifunctional groups, three new MOFs, [Co(bimip)(H₂ O)_0.5 ]⋅0.5 H₂ O (1), [Zn(bimip)] (2), and [Mn(bimip)(H₂ O)₂ ]⋅H₂ O (3), have been solvothermally synthesized in different solvent systems. H₂ bimip displays three different coordinated modes through the imidazolyl and carboxyl groups, and different cis-cis and trans-cis configurations, which result in distinct 3D topological frameworks: a (4,8)-connected scu net for 1; a twofold interpenetrated (4,4)-connected pts net for 2; and a four-connected sra net for 3. Compounds 1 and 3 show antiferromagnetic properties, and 2 emits strong solid-state blue luminescence. Compound 1 shows good chemical stability in acidic and basic environments and in boiling water. Additionally, the polar channels in 1, which are decorated by uncoordinated carboxylate O atoms and imidazolyl fragments, allow it to adsorb CO₂ molecules selectively over CH₄ , and the CO₂ binding sites in the framework were distinguished by molecular simulations.