Templating species, interaction with zeolites

Role of alkali and NH cations in the crystallization of ZSM-5 Introduced in an aqueous (alumino) silicate gel (sol), the bare alkali cations will behave in various ways firstly, they will interact with water dipoles and increase the (super) saturation of the sol. Secondly, once hydrated, they will interact with the aluminosilicate anions with, as a result, the precipitation of the so formed gel (salting-out effect). Thirdly, if sufficiently small, they also can order the structural subunits precursors to nucleation species of various zeolites (template function-fulfilled by hydrated Na+ in the case of ZSM-5 (11,48)). ... 

An interesting idea would thus consist in a functionalization with aromatic compounds bent around the z-axis. These should interact especially well with the 7t-system of the nanotubes, possibly even featuring certain selectivity for nanotubes with different diameters. A first attempt of this kind has been presented just recently. A belt-shaped aromatic molecule has been put over a fullerene here (refer to Section 2.5.6). Such a procedure should in principle be applicable to nanotubes as well. A success in performing this reaction would mean a big step toward a size-selective functionalization and possibly even toward a directed separation of individual species. Here an interaction with aromatic compounds immobilized within tubular templates, for example, within zeolites, would be another conceivable strategy. 

Pr4N+ cations were recognized to form complexes with silica-te (46) or aluminosilicate (23) species and subsequently to cause replication of the so formed framework structure via stereo-specific interactions (template effect). During this process, they are progressively incorporated and stabilized within the zeolite framework (1 1,47,48). Rollmann (37) has shown that initial Pr +/... 

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