Catalyst research, chiral molecular complexes

The discovery, in the mid-eighties, of the remarkable activity of TS-1 as a catalyst for selective oxidations with aqueous H2O2 fostered the expectation that this is merely the progenitor of a whole family of redox molecular sieve catalysts with unique activities. However, the initial euphoria has slowly been tempered by the realization that framework substitution/attachment of redox metal ions in molecular sieves does not, in many cases, lead to a stable heterogeneous catalyst. Nevertheless, we expect that the considerable research effort in this area, and the related zeolite-encapsulated complexes, will lead to the development of synthetically usefril systems. In this context the development of chiral ship-in-a-bottle type catalysts for intrazeolitic asymmetric oxidation is an important goal. Such an achievement would certainly justify the appellation mineral enzyme . 

There are thousands of discoveries in molecular science reported every year but very few of these are destined to promote a new generation of research activity. The serendipitous preparation of di-benzo-18-crown-6 1 by Pedersen in 1967 [1] and the subsequent discovery [1,2] that 1 and other crown ethers selectively complex biologically relevant alkali and alkaline earth cations was, however, the catalyst for a huge explosion of activity in the field of host-guest or supramolecular chemistry. The resulting inspired and innovative work by Lehn [3,4] on, in particular, the 3-dimensional bicyclic cryptands (e.g., 2) and by Cram [5] on chiral crown ethers and rigid spherands (e.g., 3) was recognised by the award to Pedersen... 

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