Three‐Dimensional Framework with Channeling Cavities for Small Molecules: M2 (4, 4′‐bpy) 3 (NO3) 4·xH2On (M Co, Ni, Zn)

Reversible adsorption of gases distinguishes the coordination polymers M2 (4, 4′-bpy) 3 (NO3) 4 (H2O) xn (M = Co. , x = 4; M = Ni, x = 4; M = Zn, x = 2), which are formed from M (NO3) 2 and 4, 4′-bipyridine in acetone/ethanol. The channeling cavities in the crystal frameworks (shown schematically on the right) have dimensions of about 3 × 6 Å along the a axis and about 3 × 3 Å along the b axis, and reversibly adsorb CH4, N2, and O2 in the pressure range of 1–36 atm without deformation of the crystal framework.