DABCO molecule in the M₂(C₈H₄O₄)₂·C₆H₁₂N₂ (M = Co, Ni, Cu, Zn) metal-organic frameworks

The review reports recent progress in experimental and theoretical studies of structure and properties of the C₆H₁₂N₂ molecule (DABCO) in metal-organic frameworks M₂(C₈H₄O₄)₂ C₆H₁₂N₂, where M = Co, Ni, Cu, Zn (M-DMOFs), as well as in the gas and crystalline phases. M-DMOFs belong to a new class of compounds which are considered promising materials for sorption, catalysis, selective separation, and demonstrate other remarkable properties. We review recent research on phase transitions and effect of guest molecules on properties of M-DMOFs. Thermodynamic and nuclear magnetic resonance studies of M-DMOFs indicate quantum tunneling between twisted forms (chiral isomers) of the DABCO molecule with D₃ symmetry, which stops at certain low temperature. This opens an opportunity for study and control of balance between chiral isomers.