Supramolecular photo sensitizer

Jiang J, Kasuga K, Arnold DP (2001) Sandwich-type phthalocyaninato and porphyrinato metal complexes. In Nalwa HS (ed) Supramolecular photo-sensitive and electroactive materials. Academic, New York, pp 113-210... 

A lot of photoreactions occurring in the atmosphere, hydrosphere, and soils ensure the health, comfort, and welfare of human beings, creatures, and the environment. These processes are mostly driven by coordination compounds of transition metals, which play the role of (photo)catalysts or (photo)sensitizers. There is also increased understanding of the role of supramolecular inorganic systems in their interaction with light and the great variety of processes that may ensue. 

As well as influencing chromophore types and levels, variations in production conditions result in fibers of varying morphology (orientation, crystallinity, and supramolecular order) (3). Because morphology itself may markedly effect photooxidative sensitivity, the extent of this effect was explored by first studying the susceptibility of the various filaments to y-initiated oxidation. The y-initiation is believed to be completely random and it is not dependent on trace quantities of chromo-phores or the build-up of oxidation products, in contrast to photooxidation, yet it is followed by the same propagation and termination steps as photo-initiated oxidations (2,4). 

The examples of photo-induced trans-to-cis isomerization of azobenzene dyes described above are very rare and valuable in supramolecular assembled systems, because the difficulty of the photoisomerization of the azobenzene moiety has been recognized in micellar and monolayer supramolecular systems [86,87]. In addition, other azobenzene-containing organogels, in which the trans-azobenzene moieties are tightly packed in the organogel supramolecular structme, did not show any photo-induced trans-to-cis iso-merizations [59]. Presiunably, in 22b and 44 there is sufficient room for the isomerization aroimd the azobenzene moiety. Thus, photo-induced isomerization is very sensitive to the organogel structure. 

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