Four 3D Cd(II)-Based Metal Organic Hybrids with Different N,N′-Donor Spacers: Syntheses, Characterizations, and Selective Gas Adsorption Properties

Four new metal organic frameworks with bivalent cadmium,
disodium
succinate (Na2suc), and four different N,N′-donor
ligands, i.e., {[Cd­(L1)­(suc)]­·(H2O)3}n (1), {[Cd­(L2)­(suc)]­·(H2O)2}n (2), {[Cd­(L3)­(suc)]­·(H2O)4}n (3), {[Cd3(L4)3(suc)2(H2O)2]­·(NO3)2 (H2O)4}n (4) [L1 = 2,5-bis-(4-pyridyl)-3,4-diaza-2,4-hexadiene,
L2 = trans 4,4′-azobispyridine, L3 = 2,5-bis-(3-pyridyl)-3,4-diaza-2,4-hexadiene,
L4 = 1, 2-bis­(4-pyridyl) ethane and suc = succinate dianion] have
been synthesized at room temperature and characterized by single-crystal
X-ray diffraction and other physicochemical methods. Structure determination
reveals that compounds 1 and 2 show honeycomb-like
three-dimensional (3D) architecture with water-filled channels. The
dehydrated frameworks of 1 and 2 exhibit
hydrogen and carbon dioxide adsorption properties. In compound 3, change of linker (linear to bent) led to the blockage of
such regular channels which also affected the porosity and adsorption
properties of its dehydrated framework. In 4, the used
spacer is linear but the resulting 3D framework contains blocked channels
filled with nitrate (NO3–) anions and
lattice water.