Syntheses, Structures, and Properties of Four Metal-Organic Frameworks Based on a N-Centered Multidentate Pyridine-Carboxylate Bifunctional Ligand

Four new metal-organic frameworks have been synthesized under hydrothermal conditions by the self-assembly of a N-centered multidentate bifunctional ligand (H2L: 4,4'-((4-(pyridin-4-yl)phenyl)azanediyl)dibenzoic acid) with different N-containing heterocyclic coligands (BIMB = 4,4'-bis((imidazol-1-yl)methyl)biphenyl, BPY = 4,4'-bipyridine, BIP = 1,4-bis(imidazol-1-yl)phenyl) and transition metal salts (Co(NO3)(2)center dot 6H(2)O, Zn(NO3)2 center dot 6H(2)O). They are [Co(L)(BIMB)(0.5)(H2O)]center dot 2DMF (1), [Co(L)(BPY)(0.5)(H2O)(2)]center dot 3DMF center dot 2H(2)O (2), [Zn-2(L)(2)]center dot 4DMF center dot 3H(2)O (3), and [Zn-2(L)(2)(BIP)]center dot 2DMF center dot 2H(2)O (4). Compound 1 is an infrequent 3,4-connected self-penetration three-dimensional (3D) architecture. Compound 2 has been classified as a trinodal (3,4,4)-connected 3D sqc69 framework. Compound 3 displays a 2-fold interpenetrating 3D net based on the [Zn-2(CO2)(4)] units which are connected by L2- ligands. For compound 4, the larger potential voids lead to a 4-fold interpenetration, which can be classified as type IIIa. In addition, their thermal stability, the adsorption isotherms, and optical properties have been studied in detail.