Natural systems, supramolecular photochemistry

Since the coining of the term supramolecular chemistry - defined as the chemistry of molecular assemblies and of the intermolecular bond by Lehn in 1978 - supramolecular chemistry has undergone a spectacular expansion. A wide variety of chemical systems have been developed, which, although different in nature to the former systems, currently are also considered as real supramolecular ensembles. One of most remarkable examples is the field of supramolecular photochemistry, where, in a broader sense, a supramolecular compound is defined as a group of molecular components that contribute properties, which each component possesses individually, to the whole assembly. 

Most chemical reactions and spectroscopic work are carried out in solution. However, recent investigations have shown great potential for solid-state chemistry. First, supramolecular systems consisting of more than one kind of molecule exhibit characteristics that are different from those of the individual molecules. We have recently reported inverted supramolecular chirality of bis(zinc octae-thylporphyrin), an enantiopure monoamine system in solution and in the solid phase [3]. Secondly, solid-state reactions occur more frequently than previously envisaged [4-7], and they may give products in high yield that are unobtainable by reaction in solution. They are kind to the environment because of their solvent-free nature and hence are currently attracting attention from the industrial sector as well. Compared with thermal or chemical reactions, photochemistry is particularly... 

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