Electronic properties tailor-made

An important challenge in the design of novel conjugated polymers is the synthesis of materials with tailor-made solid-state electronic properties. This section outlines the synthesis of the most significant classes of poly(para-phenylenevinylene)s (PPVs), poly(para-phenylene)s (PPPs), and related structures. Furthermore, this review demonstrates that the chromophoric and electronic properties of conjugated rr-systems are sensitive to their molecular and supra-molecular architecture. 

With the aim of preparing photoinduced electron transfer devices or simply to be used as fluorescent reporter groups, the synthesis and utility of pyrene-L-alanine have been reported on several occasions. Regarding the development of charge-transfer devices, it was shown that intramolecular electron transfer occurred in 310- and a-helical peptidic systems, such as 182 and 185, between a pyrene and a dimethylaminophenyl chromophore (Scheme 51).[95 101] The rates depend on the relative orientation of the chromophoric side chains and on the framework conformation. Therefore, the preparation of tailor-made charge-transfer devices with tunable properties can be envisaged. 

Until relatively recently, the only zeolites which were known were those which occur naturally as minerals, however, considerable advances have been made in the area of zeolite synthesis, and this has led to an enormous effort being channelled into the development of new and novel zeolite structures. There has also been a great deal of interest shown in incorporation of elements other than silicon and aluminium to tailor the electronic properties for specific applications. The major advantage of synthetic zeolites over naturally occurring ones is that, by a judicious choice of reactants, conditions, etc., it is possible to create structures of the required composition and dimensions. 

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