Cloverite synthesis

The synthesis of Cloverite is also unique in that it established the utility of HF in zeolite molecular synthesis. In the case of silicates, either hydroxide or HF serve to mineralize the silica. That is not needed in the GaP04 synthesis but the F ion plays an important role in stabilizing the structure. The fluoride ion becomes encapsulated in the D4R units. It has been suggested that fluoride ions in fact direct... 

The fluoride route of synthesis seems very rich and already provided four among the six most open frameworks described up to now in the litterature in the category of microporous compounds (0 < A) VSB-1 [22] cloverite [11], ULM-5 [23] and ULM-16 [24] with tunnels limited by 24, 20,16 and 16 polyhedra respectively. These four solids are really porous, the porosity being generated by the elimination of the template either by thermal or chemical methods which preserve the inorganic framework. 

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. 

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. 

The available intrazeolitic space should be sufficient to accomodate a complex with a diameter of approximately 1.5 nm. This seems possible in faujasite type zeolites as weli as in very large pore AlPO -n molecular sieves or substituted anaiogs. VPI-5 is a candidate (23). For AIPO4-8 molecular graphics analysis predicts - as is confirmed by synthesis attempts - that accomodation of the complex for sterical reasons in this molecular sieve is impossible. The Cloverite material, the structure of which has been described elsewhere in this volume, also is a potentiai support. 

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