Syntheses and Characterizations of Two 3D Cobalt−Organic Frameworks from 2D Honeycomb Building Blocks

The hydrothermal reaction of Co(NO 3 ) 2 ·6H 2 O, imidazole 4,5-dicarboxylic acid (H 3 IDC), and 4,4‘-bipydine (bipy) under different conditions affords two interesting metal−organic compounds, {[Co 3 (IDC) 2 (4,4‘-bipy)(H 2 O) 4 ]·2H 2 O} n ( 1) and {[Co 3 (IDC) 2 (4,4‘-bipy) 3 ]·6H 2 O·DMF} n ( 2 ), both of which have been structurally characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy, and thermogravimetric analysis. Temperature-dependent magnetic susceptibility for 1 and 2 were also studied. The “all-chair” two-dimensional honeycomb networks, structurally analogous to CF x, were linked by the bridging 4,4‘-bipy ligand in compound 1 to give rise to a 2-fold interpenetrated 3D architecture. Compound 2 features a three-dimensional open framework with hexagonal channels, generated from two-dimensional graphene-like layers pillared by 4,4‘-bipy. The simplest cyclic motif of the 2D networks in 1 and 2 is a 24-membered hexagonal ring consisting of six Co(II) cations and six IDC 3- trianions.