dimensional network of edge- and vertex-sharing NiO 6 octahedra. The methylene
groups of the succinates create a very hydrophobic channel system, quite unlike
those found in traditional zeolitic materials. Nickel succinate retains its crystal
structure up to 400
C, as verified by in situ XRD and TGA studies, supporting
expectations of improved thermal stability for hybrid systems with 3D M–O–M
connectivity.
Recent work has offered several insights as to why these materials exhibit higher
M–O–M dimensionality than is typically found in hybrid carboxylate systems. Livage and Fe ´rey observed that the use of hydrothermal synthesis favors increased
condensation of cobalt centers, resulting in the higher M–O–M dimensionality
than phases obtained through reactions near room temperature [149]. More recent
systematic studies in the cobalt succinate system have further clarified this result
[150]. Forster et al. demonstrated that five unique cobalt succinate structures could
be synthesized using identical starting mixtures by varying only the temperature.
The resulting series of cobalt succinates show a progressive decrease in water content with increasing temperature, as would be expected based on entropic considerations. Octahedral coordination is maintained by increased sharing of carboxylate
oxygen atoms between cobalt centers, resulting in the 2D M–O–M materials seen
at higher temperatures. This trend may be seen in Table 18.3.
Based on these and other structures, Forster and Cheetham have proposed that
Fig. 18.9. The hybrid metal oxide nickel succinate. NiO 6
octahedra are shown in gray, oxygen atoms are drawn as dark
gray spheres, and carbon and hydrogen atoms are drawn as
gray spheres.
18.6 Hybrid Nanoporous Materials 613
groups of the succinates create a very hydrophobic channel system, quite unlike
those found in traditional zeolitic materials. Nickel succinate retains its crystal
structure up to 400
C, as verified by in situ XRD and TGA studies, supporting
expectations of improved thermal stability for hybrid systems with 3D M–O–M
connectivity.
Recent work has offered several insights as to why these materials exhibit higher
M–O–M dimensionality than is typically found in hybrid carboxylate systems. Livage and Fe ´rey observed that the use of hydrothermal synthesis favors increased
condensation of cobalt centers, resulting in the higher M–O–M dimensionality
than phases obtained through reactions near room temperature [149]. More recent
systematic studies in the cobalt succinate system have further clarified this result
[150]. Forster et al. demonstrated that five unique cobalt succinate structures could
be synthesized using identical starting mixtures by varying only the temperature.
The resulting series of cobalt succinates show a progressive decrease in water content with increasing temperature, as would be expected based on entropic considerations. Octahedral coordination is maintained by increased sharing of carboxylate
oxygen atoms between cobalt centers, resulting in the 2D M–O–M materials seen
at higher temperatures. This trend may be seen in Table 18.3.
Based on these and other structures, Forster and Cheetham have proposed that
Fig. 18.9. The hybrid metal oxide nickel succinate. NiO 6
octahedra are shown in gray, oxygen atoms are drawn as dark
gray spheres, and carbon and hydrogen atoms are drawn as
gray spheres.
18.6 Hybrid Nanoporous Materials 613