Synthesis, crystal structure and characterization of two new cobalt(II) metal–organic frameworks with 1,4-bis((1h-imidazol-1-yl)methyl) benzene and 1,3,5-tris(1h-imidazol-1-yl)methylbenzene ligands

Two novel CoII metal–organic frameworks Co (BIMB) 2 (H2O) 2 (SO4) ·EG·3 H2On (I) and Co (TIMB) 2 (SiF6) n (II) were hydrothermally synthesized by corresponding metal salt with organic ligands 1, 3, 5-tris (1H-imidazol-1-yl) methylbenzene (TIMB) or 1, 4-bis ( (1H-imidazol-1-yl) methyl) benzene (BIMB). Crystal structural analysis reveals that they exhibit varied structures. Compound I contains two crystallographically unique CoII centers, each lying on an inversion center and having a slightly distorted octahedral environment. The BIMB ligands link the CoII cations to generate a three-dimensional porous framework with a 4-connected uninodal (65. 8) topology. Compound II exhibits a two-dimensional sheeted metal-organic structure running parallel to the (0 0 1) plane, in which TIMB ligands join Co2+ centers having a six-coordinated octahedral structure. In the solid state, adjacent sheets are further bridged by guest SiF6- anions via C–H…F hydrogen-bonding interactions, giving rise to a three-dimensional supramolecular network structure with a 2-nodal (3-c) 2 (6-c) net. The topological analysis suggests that the point Schläfli symbol of compound II is (43) 2 (46. 66. 83). In addition, their thermal stabilities have also been investigated.