Gallophosphate cloverite

The structure of Cloverite (IZA structure code, CLO) has limited thermal stability in air, which is not surprising for gallophosphates. It has been shown that Cloverite is stable in ambient air or a vacuum up to 500°C, but if the molecular sieve is cooled below 100°C, the structure collapses (153). If the calcined Cloverite is immediately placed in hydrocarbon solvents it can be stored at RT for several months. 

FIGURE 7.25 The framework of the synthetic gallophosphate, cloverite, represented as shaded spheres of van der Waals radii. (From C.R.A. Catlow (ed.) (1992) Modelling of Structure and Reactivity in Zeolites, Academic... 

The physical-chemical properties of a synthetic gallophosphate molecular sieve, the 30-A supercage cloverite , have been assessed [18]. Instead of attempting to list the burgeoning number of fullerene publications, attention is drawn to the formation and characterization of fullerene-like nanocrystals of tungsten disulfide [19,20]. Preparation, characterization and utilization of carbon nanotubes have been the subject of a number of reports from several laboratories [21-27]. 

Fig. 18.4. The gallophosphate cloverite. Gallium polyhedra are shown in gray and PO4 tetrahedra are represented in light gray. Water molecules and the organic template have been omitted for clarity.

Cloverite is a gallophosphate molecular sieve with 20-ring channels. The Ga04 tetrahedra and PO4 tetrahedra with terminal -OH groups alternate strictly to produce an interrupted three-dimensional open framework. Figure 2.57 shows a projection of cloverite along the [100] direction with a pore opening in the shape of a four-leafed... 

Since the discovery of gallophosphate cloverite with 20-ring pore openings, a variety of open-framework gallophosphates have been reported with extra-large pores, such as... 

Q. Huo and R. Xu, Synthesis of the Gallophosphate Molecular Sieve Cloverite with 20-ring Channel from an Alcoholic System. J. Chem. Soc., Chem. Commun., 1992, 1391-1392. 

Larger pore materials have followed, for example, cloverite, a 20 tetrahedral atom gallophosphate material that has a four leaf clover shaped pore opening... 

Fig. 17. P MAS NMR spectrum of the gallophosphate cloverite (solid line) and its components (dashed-dotted) derived by decomposition [149]. At the top, a structural element of cloverite...

In the last two decades there has been considerable progress in the synthesis of molecular sieve materials. One result of these efforts is cloverite, a large-pore gallophosphate molecular sieve with a 20 T-atom cloverleaf-shaped entrance into a supercage of about 30 A diameter, which has attracted attention not only due to potential novel adsorption and catalytic properties and the uptake of bulky adsorbates, but also as a host for the preparation of semiconductor nanoclusters, as an example for the development of new advanced materials. 

Extra-large-pore zeolites (at least 14-membered rings with pore sizes around 1.0 nm)—e.g., aluminosilicates CIT-5, UTD-1. aluminophosphates (VPI-5, JDF-20, gallophosphate. cloverite). 

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