Co-MOFs Containing Flexible ,-Alkane-dicarboxylates and Bis(imidazole) Ligands: Synthesis, Structure, and Properties

Three structurally related flexible bis(imidazole) ligands reacted with Co(NO3)(2)6H(2)O and succinic acid (L-1) to yield three new metal-organic frameworks {[Co(L-1)(L-2)](H2O)}(n) (1) [L-2 = 2-bis(imidazol-1-yl)ethane], {[Co(L-1)(L-3)](H2O)}(n) (2) [L-3 = 1,4-bis(imidazol-1-yl) butane], and {[Co(L-1)(L-4)](H2O)}(n) (3) [L-4 = 1,4-bis(2-methyl-imidazol-1-yl)butane], respectively. These complexes were synthesized under solvothermal conditions and characterized by elemental analysis, IR spectroscopy, single-crystal and powder X-ray diffraction, as well as thermal analyses. Interestingly, the ligands in these complexes exhibit different conformations and further cause three different configurations. Complex 1 shows a three-dimensional (3D) framework, which is connected by two-dimensional (2D) layer structures through hydrogen bonds. Complex 2 is a diamond structure with threefold interpenetration. Complex 3 is a 3D framework linked by hydrogen bonds like complex 1.