Organic cations as templates

In summary, we have shown that novel anionic host lattices can be constructed from urea, thiourea, or selenourea molecules and various anions as building blocks, which readily adopt different topologies for the accommodation of tetraalkylam-monium ions of various sizes. By employing organic cations as templates and suitable counter anions as an ancillary host material, with or without neutral molecules such as H2O as a third component, the lattice engineering of new urea, thiourea, and selenourea inclusion compounds by self-assembly may be further explored. 

During the last few years, many attempts have been made to design specific syntheses of fluorine compoimds with, for instance, oligomeric anions, linear chain anions, layer structures, or framework structures using organic amines as templates, which serve mostly, after protonation, at the same time as counter cations (see Refs. 5,17,18, or for oxyftuorides with open framework structures Ref 19). 

Though the term hybrid is not sharply defined and is a matter of taste, it is used here to summarize compounds containing besides an inorganic part - here a fluoride species-an organic component. This may be an organic cation, a template molecule, or an organic ligand. As there is... 

The first step consists in the synthesis of molecular sieve materials. This field has been widely broadened in the past two decades for synthetic materials since the introduction by R. Barrer of organic compounds such as quaternary amine cations as template molecules. Other presentations in this Advanced Study Institute are dealing with synthesis of molecular sieves. 

The examples just presented give initial impressions of how DNA can be utilized as a template in the synthesis of nanometric and mesoscopic aggregates. However, the studies emphasize the importance of fundamental research on the interaction between DNA and the various binders, such as metal and organic cations. Of particular importance are the consequences of binding events on the structure and topology of the nucleic acid components involved. 

The zeolites discussed so far have all relied on exotic organocations to function as SDAs. However, sometimes the inorganic cations can have a greater influence as demonstrated by the 12-MR zincosilicate, VPI-8 (65-68). The synthesis of VPI-8 still requires an organic additive but its role as template may be as a void filler. A recently determined model for the structure of VPI-8 viewed along the 001 direction is shown in Fig. 10 (69). Much like SSZ-31, the structure of VPI-8 involves ID channels running in parallel that are defined by odd-shaped 12-MR structures (6.2 x 5.97 x 5.88 A). An unusual feature of this structure is the pinwheel building unit that is composed of four 5-MR stmctures surrounded by another four 5-MR structures. 

---