Clusters pillared

A notable example is the wheel-shaped cationic cluster [Er36([X3-OH)3o([i3-0)6(BDC)6] " " (Figure 6.41) present in the lanthanide-transition metal sandwich framework comprising (Cus) cluster pillars and layered networks of (Erse) wheels [25, 77]. The Er + ions are linked by hydroxo and oxo bridges to give two types of smaller cluster cores cubic [Er4([i3-0)([i3-0H)3] + (Ere) and dimeric [Er2([i3-OH)2]" + (Er2) cores (Figure 6.41a). Different from the familiar cubane [Ln4([X3-OH)4] + which contains four [X3-OH groups, the present (Er4) cluster... 

Thanks to the synergistic coordination of BDC and IN, lanthanide-transition metal sandwich framework comprising CU3 cluster pillars and layered networks of Erag wheels has been reported. X-ray diffraction studies revealed a stunningly beautiful 3D network structure composed of a 2D network of wheel-shaped cationic clusters [Er36(/i3-OH)3o(/is-... 

Figure 4.1 clearly illustrates the modular construction of MOFs, with ligands used as pillars and metal clusters as node points. One unique feature of MOFs seems to be the possibihty to systematically modify their lattice. For instance, by replacing the terephthalate ligands of MOF-5 (Figure 4.1) with different dicarboxylate ligands, a family of isoreticular metal-organic frameworks (known in literature as the... 

At MAT conditions, montmorilIonites pillared with alumina clusters, and having similar surface area, generate (at a given conversion level) similar amounts of coke (when used to crack gas oil) irrespective of the iron content of the parent bentonite. Thus, the presence of iron cannot be used to explain the high tendency for coke (and light gas) make of pillared clay catalysts. 

These clays have been hybridized with diverse structural types of components such as nanoparticles, clusters, complex compounds, polymers, molecules, and ions. Their potential apphcations are found in many fields as inorganic catalysts, adsorbents, ceramics, coatings, and even drug delivery carriers. Various preparation methods have been developed such as pillaring, intercalation, and delamination techniques. The representative examples include organic-clay hybrids," metal oxide-pillared clays, " and bioclay hybrids. ... 

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