An Introduction to Supramolecular Photochemistry

In the modified zeolite sensitization study, a significant enhancement of product ee was reported to occur by the introduction of a chiral sensitizer into the zeolite supercages that otherwise give an almost racemic product [47]. Further supramolecular approaches to the enantiodifferentiating photosensitization will lead to more solid conclusions on the mechanisms and factors that control supramolecular photochirogenesis and open a new channel to asymmetric supramolecular photochemistry in the near future see Chap. 9. 

Molecular photochemistry of porphyrins and metalloporphyiins has exhibited novel aspects even at the current state whereby comprehensive efforts have been accumulated to understand their chemistry in the excited states. As described in the Introduction, the chemistry of porphyrins is inherently an aspect of supramo-lecular chemistry, since the central metal ion, porphyrin macrocycles, and axial ligands are all associated with coordination interaction. Porphyrin chemistry has multiple aspects of chemistry on 1.) the large n-electron system, 2.) the substituents, 3.) the central metal ion, 4.) the axial ligands, and S.) the special space for chemical reactions provided by the porphyrin plane and the metal-axi ligand microenvironment. The molecular photochemistiy based on their characteristic electronic structures, photophysical properties, and redox properties, which are summarized in Tables 1-3, has been surveyed in this chapter. Comprehensive understanding of porphyrin photochemistry would provide impetus or creation of unit devices in prospective supramolecular systems. Though we are obliged to say that we have not yet had a satisfactory supramolecular system, recent... 

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